Canberra have sealed their place in the NRC semi-finals after beating Sydney 36-26 in a slog at Viking Park.
Despite sprinting to a 12-0 lead early and taking a 10-point buffer to the break, the Vikings were not out of the woods until the dying stages when awarded a penalty try following a TMO review.
Despite having just one win to their names this season, Sydney fought doggedly and took the lead midway through the first term when Canberra had Wallabies half Joe Powell in the bin.
Down again in the second half, they fought back to within eight points before the penalty try put the result beyond doubt, helping Canberra cement their semi-final spot and nominally jump into second place on the ladder, ahead of the NSW Country Eagles, who play Queensland Country on the Gold Coast on Sunday.
The Vikings scored after just three minutes, their try coming against the run of play after they pounced on a loose ball, with Will Miller racing clear before picking up Darcy Swain running a neat angle to the line.
Sydney compounded their error when Junior Wallabies playmaker Ben Donaldson put the ball dead from the restart and were made to pay almost immediately, with the Vikings scoring from the resulting scrum.
Halfback Joe Powell linked with fullback Tom Banks bursting into space before he found winger Mack Hansen racing down the flank to score.
Just as the Vikings looked to be comfortably on top though, Sydney hit back, earning a penalty try, with Powell also sent to the sin bin for deliberately collapsing the visitors' rolling maul.
With Powell still in the bin, Sydney scored when lock Ryan McCauley sloppily picked up a loose pass and trotted over, many of the defenders dropping off believing the ball had been knocked on.
Will Harrison's conversion gave Sydney a 14-12 lead, with the Vikings paying dearly for Powell's indiscretion.
The visitors looked set to press for another score late in the half after opting for a lineout rather than a shot at goal after a penalty deep in their territory.
But when the ball popped out of the resulting maul, the Vikings counter-attacked, with tom Wright finishing off a great team effort for a try that returned Canberra to the lead.
They were in again before the break, with Banks capping a patient shift by dotting the ball down just before the halftime hooter to give the home side a 10-point lead.
The second half was more of an arm wrestle, with neither side able to get an advantage until Wright notched his second try in the 57th minute, managing to hold off two defenders to cross, having managed to avoid crossing into touch.
But when flanker Hugh Sinclair drove over, Sydney was just eight points down and remained in contention.
They were unable to capitalise on their chances though and the Vikings sealed the win when the Vikings were awarded a penalty try in the dying minutes.
Replacement flyer George Morseu looked to have scored in the 74th minute after beating the cover defence of Sydney fullback Will Harrison.
But a check by the TMO revealed Morseu had stepped into touch when tackled by Harrison, whose initial contact was ruled to be above the shoulder, resulting in a penalty try to the Vikings, with a yellow card handed to the Junior Wallabies playmaker.
Sydney scored a consolation try right on fulltime, replacement Declan Moore completing their attacking raid on the siren.
Canberra Vikings 36
Tries: Swain, Hansen, Wright 2, Banks, penalty try
Cons: Kuenzle 2
Yellow card: Powell 15'
Tries: Penalty try, McCauley, Sinclair, Moore
Cons: Harrison 2
Yellow card: Harrison 74'