Australia will play France in their Cup quarter-final on Saturday after two wins from three games on day one.
The Aussies beat China and Spain before losing to USA 19-12 on the final game of the day.
New Zealand were the only undefeated team after the pool stages, setting up a final eight clash with Canada, who had an uncharacteristically tough day on the field.
Ireland take on Spain and Russia meets the USA in the remaining two quarter-finals.
8:08pm - Cup QF schedule
12:50pm - New Zealand vs Canada
1:12pm - Russia vs USA
1:34pm - Ireland vs Spain
1:56pm - Australia vs France
8:04pm - Aussies positive despite final pool loss
Aussie women’s Sevens coach John Manenti will be checking the weather forecast more closely on Saturday after rain put a dampener on his side’s campaign in Sydney.
The Aussies won their first two matches against Spain and China before being outmuscled against the USA in their final match of the day, 19-12.
Australia had a host of handling errors against the USA in increasingly wet conditions and it was something Manenti said they would look at overnight.
"We worked hard to get a run there in the second half and I think in a couple more minutes we probably score again but I suppose the big thing is we started the day well and we put ourselves in a position that we're going to be playing tomorrow and we know that day two is where the action happens so I'm not too disappointed," he said.
"I thought they showed some good courage, USA bigger side and that pick-and-go football that they played in the wet suited them.
"That's the luck of footy and the conditions you play in and we put in a fair few plans around playing them in the hot and dry weather and having the fatigue in their big girlsand obviously that never eventuated but like i said we'll learn a lot from playing in that wet."
Australia will play France in their cup quarter-final on Saturday and Manenti is expecting another physical outing against the French, who they last played in last year's Sevens World Cup.
"They're a very physical side and play very hard on the ball," he said.
"They're pretty strong across the park with their speed too.
"We've had a reasonable look at them over the last few tournaments though we haven't met them but we've been preparing to play them so we're looking forward to having a shot at them."
7:17pm - ROUND THREE
Australia has topped Pool C despite going down to the USA in their final pool game of the day, 19-12.
The Aussies came into the final round as the only undefeated team in the pool but were caught on the back foot by the fast-starting USA, putting the sides on equal points after the final game and sweating on the result of Spain vs China.
Spain edged China out by two points, drawing level on points with USA and Australia and it was points difference that propelled the Aussies to the top of the pool
The USA drew first blood in the third minute and some sloppy Australian work off the next restart put the hosts under immediate pressure again.
America made the Australians pay straight away for their mistakes with Kirsti Kirshe barreling through to score.
Australia’s long passing game cost them in slippery conditions with a number of errors coming from tactics which they use to lay an attacking platform.
Naya Tapper slipped through some inaccurate Aussie defence for a third USA try before the break.
Australia looked like creating some attack but mistakes allowed the USA to find turnovers and capitalise.
It took until the 11th minute for Vani Pelite to finally break through the USA defence after a strong running line from Alicia Quirk opened up a gap for her teammate.
Emma Tonegato added to the score on the final siren but it was too little too late for the Aussies.
Australia will face France if they end up on top of the pool or Russia if they progress in second, a finish that depends on the final game of the day.
New Zealand completed a pool clean sweep with a 29-0 win over England to finish their opening day of play.
France had an emphatic 53-0 win over PNG to cement their second spot in the pool.
Sydney's 2017 champions Canada face a nervous wait to find out if they will make the Cup quarter-finals after a second upset in three games on Friday.
Canada went down to Russia in their third game to relegate them to third in the pool and leave them awaiting other results to determine whether they will take the final spot in the knockouts.
Ireland edged out Fiji in the final game of the day, beating the Pacific Islanders 24-19 to go top of their Sydney 7s pool.
The Irish will play the best third-placed side in the quarter-finals on Saturday afternoon.
Ireland 24 - Fiji 19
Canada 7 - Russia 12
France 53 - PNG 0
New Zealand 29 - England 0
Australia 12 - USA 19
China 12 - Spain 14
5:17pm - Aussies gearing up ahead of final game
Australia might be one game clear on top of their Sydney 7s pool but Vani Pelite says they can't underestimate their final round opponents USA as they vie to finish first.
The Aussies have had a mixed recent history against the USA but the Americans suffered a surprise loss against Spain in their second round clash.
Pelite dismissed the idea that the Americans were in any way invaluable
We can't underestimate them at all after that last game."
The Aussies looked more connected in their second game after a rusty first outing and Pelite said they were beginning to adjust to life without injured star Charlotte Caslick.
"We're building every game so it's good to see and the girls are starting to find their mojo and their combinations which is really great to see.
"We're still working on our combinations a little bit. Obviously Charlotte played a massive key part but we're really finding our feet out there at the moment and we're only going to keep building as the tournament goes on."
4:47pm - ROUND TWO
Australia are in the box seat to top their Sydney 7s pool after a 24-7 win over China in their second game.
The Aussies were straight out of the blocks with tries for Vani Pelite and Alicia Quirk in the opening three minutes.
Pelite threw the final pass for Sharni Williams to slip through the gap in the last minute of the first half and give the Aussies a 17-0 at the break.
Ellia Green lit up the Spotless crowd with a spectacular solo effort on the left edge midway through the second half.
Emma Sykes ran down one Chinese attacker but they managed to get over in the dying moments of the match to break a deadlock.
Australia is the only undefeated side in their pool after two rounds and they will likely face either England or France in a quarter-final.
In the earlier matches, Spain scored a famous victory over the USA in the second match of their Sydney campaign, throwing the race for second in Pool A wide open.
New Zealand have gone two-from-two with a 31-7 win over France in their second round.
England bounced back in their second game to beat PNG 34-5, despite the Papua New Guineans scoring the first try of the match.
Ireland sprung a massive upset over World Series heavyweights Canada with a 15-14 win in round two.
The Irish built into the game slowly and it was Amee Leigh Murphy Crowe who scored the match winner in the 10th minute.
Fiji surprised Russia with a 21-12 win to open the second round of matches in Sydney, leaving the latter's quarter-final hopes in the balance.
Russia 12 - Fiji 21
Canada 14 - Ireland 15
England 24 - PNG 5
New Zealand 31 - France 7
USA 14 - Spain 21
Australia 24 - China 7
2:43pm - Sykes satisfied with Spain win
The Aussie women were glad to take a victory in their opening match but Emma Sykes said they know there's more work to be done.
Sykes scored a try and converted each of Australia's scores in a hard-fought 19-0 win over Spain on Friday.
"It was a good win in the end, it was good we kept Spain to nil because it's the first game. So, form now on we're just looking to improve on each game but it was good," she said.
Spain has been one of the improvers on the Sevens World Series circuit in recent times and Sykes said they were prepared for the physicality of the European side.
"Spain's a very physical team and we know when we play them, we've got to be up physically when we're playing against them," she said.
"They're a team that every time you play them they're improving and so you can't go into any game on this World Series underestimating anything."
Sykes said the team wasn't feeling any kind of undue pressure coming into the competition as defending champions at their home tournament.
"Some people would think that there's pressure but going into this we're just focusing game by game and not taking in that we are the defending champs and we are playing at home but obviously that's in the back of people's minds but we're just going out there and playing game by game," she said.
2:22pm - PNG's spectacular finish
Execution: 10/10 for PNG's Fatima Rama against New Zealand.
Rama shocked the usually impenetrable Kiwis with a spectacular solo try in Sydney, finishing the score with a flourish as well.
Setting the benchmark high early.
2:10pm - ROUND ONE
Australia's women have opened their Sydney campaign with a 19-0 win over Spain but the victory did not come easily.
The Spanish defence was brutalising the Aussies early and the defending champions simply couldn’t find a way through.
Returning speedster Emma Tonegato looked threatening, with the hosts going to the winger on the left edge a handful of times, but the Spaniards stopped her short of the line at every opportunity.
It wasn’t until Ellia Green was able to scoop up a loose pill and beat her opposing defenders in the eighth minute that the Aussies found the line and that finish ignited the home side.
Emma Sykes slipped through a gap just over a minute later to stretch the Aussies’ lead.
Green put on a stepping show on the way to what looked like being her second try but she was felled short of the line and Vani Pelite finished off the ensuing chain of passes to take the gap to 19 points.
The Aussies take on China at 4:34pm AEDT in their second pool match.
In the other matches of the opening round, World Series leaders New Zealand opened their campaign with a 38-5 win over PNG.
PNG had the Kiwis level early in the piece with a spectacular runaway try and unique celebration but the Black Ferns' class shone through as they pulled away.
A double for Fanny Horta helped France to a 27-14 upset over England in their first pool match, putting the pressure on the English to keep their campaign alive.
Canada stamped themselves as the dominant Pool B team after two matches, cruising to a 36-12 win over Fiji.
Ireland and Russia opened the competition with a tense 7-7 deadlock.
It took Ireland until the 12th minute to open the scoring and Russia promptly replied to level the scores and that's where the ledger stayed.
Ireland 7 - Russia 7
Canada 36 - Fiji 12
England 14 - France 27
PNG 5 - New Zealand 38
China 10 - USA 26
Spain 0 - Australia 19
1:03pm - Phipps with the jersey honours
The Aussie women had a special guest in to present their jerseys overnight with Wallabies halfback and former Aussie Sevens player Nick Phipps doing the presentation for the side.
Home presentations are always extra important for the team with friends and family around to watch.
There will be an interesting connection for one of the Aussies as well with Evania Pelite's boyfriend Paul Titjiens, son of former New Zealand men's coach Gordon, steering PNG's women this weekend.
Tune in to Fox Sports today to watch @aussie7s girls rip in to Sydney 7s 🇦🇺 vs 🇪🇸 1:50pm vs 🇨🇳 4:43pm vs 🇺🇸 6:56pm Also a massive good luck to my partner @paulytitch for his first international 7s tournament as Head Coach of PNG Women’s. so incredibly proud of you, can’t wait to watch and support you this weekend. So special we get to share this moment together in Sydney ❤️ #aussie7s #sydney7s
11am - Aussies backing youth
The Aussie women are welcoming back Emma Tonegato to their lineup this weekend but they are still missing a host of stars with Emilee Cherry, Charlotte Caslick and Shannon Parry ruled out of the Sydney tournament.
Australia coach John Manenti has backed youngsters Lily Dick and Sariah Paki to continue their form from Dubai, picking them in the 12, and both are keen to make an impact.
10:50am - Where we stand
Sydney is the third leg of the Women's World Series and it's been all New Zealand in the first two legs.
The Kiwis have gone undefeated through every tournament in the season, and sit on top of the standings with 40 points, ahead of Canada and then USA.
The 2018 Sydney 7s final was the last time New Zealand dropped a match on the circuit, going on to win the Sevens World Cup, the Commonwealth Games and the remainder of the World Series tournaments in the 2017-18 season.
Overall World Series positions are more important than ever this season with the top four nations automatically qualifying for the Tokyo Olympics.
1. New Zealand - 40 points
2. Canada - 34 points
3. USA - 32 points
4. Australia - 28 points
5. France - 22 points
6. Russia - 20 points
7. Ireland - 16 points
8. England - 16 points
9. Spain - 7 points
10. China - 6 points