An 82nd minute drop goal to Zarn Sullivan has sealed a 20-17 win for the Blues over the NSW Waratahs at Leichhardt Oval.
In a tense first half, the boot of Jock McKenzie was the only points as the host took a 3-0 lead into the break.
However, some brilliance from Mark Nawaqanitawase got the Waratahs back into the contest as he scored a quick double.
The Blues remained calm and tries to Cameron Suafoa and Luke Romano put them in front with just five minutes remaining.
Tane Edmed looked to have sent it into extra time with a penalty but once again the Blues found a way to win late as Sullivan dropped back into the pocket and sealed the win.
"It's a disappointing finish for us at Leichhardt Oval," said Waratahs captain Jake Gordon.
"We thought we started that second half really well and put some pressure on the Blues but we weren't clinical in the last 20 minutes."
In front of a 14,681-strong Leichhardt crowd, defence was king in the first half as both teams held out waves of attacks.
The ladder leaders showed no sign of the mass changes they have made from last week's win over the Brumbies as they built pressure on the Waratahs line.
The hosts have become renowned for their goal-line defence and this showed in the first 20 minutes as they kept forcing the mistakes whilst dominating their lineout.
Darren Coleman’s men were given the perfect chance to strike when Adrian Choat found himself in the bin for a high shot, shortly followed by Akira Ioane for one too many penalties.
Down two men, the Blues held on and forced the instant turnover, outscoring the hosts during the ten minute period via a Jock McKenzie penalty.
This was the lone score of the half as the visitors went into the break full of confidence, leaving the Waratahs frustrated and searching for answers.
Needing a response, it was Nawaqanitawase that took the game over.
He dived over untouched after 50 minutes to score the first try of the match before somehow finding a way to dive over in the corner to give them a 14-3 lead.
The Blues have built their club-record winning streak on coming back from deficits and this was no different, starting with replacement forward Cameron Suafoa.
With the hosts trying to hold on, Luke Romano found the line with five minutes to go to give them the three-point lead.
The 'Tahs refused to give up and eventually earned a scrum penalty 35 metres out, with Edmed making no mistake with 90 seconds to go.
Super Time looked certain, however, the Blues mounted one last attack as they attempted to replicate last week's heroics.
With no Beauden Barrett, it was Zarn Sullivan that stepped up when it counted, guiding the field goal over the posts to break the Waratahs' hearts.
TRIES: Suafoa, Romano
CONS: Sullivan 2/2
PENS: McKenzie 1/2
DROP GOAL: Sullivan 1/1
TRIES: Nawaqanitawase 2
CONS: Edmed 2/2
PENS: Edmed 1/1
NSW WARATAHS V BLUES TEAMS
Waratahs: 15 Ben Donaldson, 14 Mark Nawaqanitawase, 13 Alex Newsome, 12 Lalakai Foketi, 11 Dylan Pietsch, 10 Tane Edmed, 9 Jake Gordon (captain), 8 Will Harris, 7 Michael Hooper, 6 Charlie Gamble, 5 Ned Hanigan, 4 Jed Holloway, 3 Archer Holz, 2 Dave Porecki, 1 Angus Bell.
Replacements: 16 Mahe Vailanu, 17 Ruan Smith, 18 Paddy Ryan, 19 Hugh Sinclair, 20 Jeremy Williams, 21 Rahboni Warren-Vosayaco, 22 Jack Grant, 23 Jamie Roberts.
Blues: 15 Zarn Sullivan, 14 Jacob Ratumaitavuki-Kneepkens, 13 Tamati Tua, 12 Corey Evans, 11 AJ Lam, 10 Jock McKenzie, 9 Sam Nock, 8 Taine Plumtree, 7 Adrian Choat, 6 Anton Segner, 5 Josh Goodhue, 4 Luke Romano (captain), 3 Nepo Laulala, 2 Ricky Riccitelli, 1 Jordan Lay.
Replacements: 16 Soane Vikena, 17 Karl Tu’inukuafe, 18 Marcel Renata, 19 Sam Darry, 20 Cameron Suafoa, 21 Akira Ioane, 22 Taufa Funaki, 23 Nigel Ah Wong.
Assistant referees: Angus Gardiner; Matt Kellahan