Crusaders full-back Leon MacDonald slotted a match-winning drop goal for his team to deny the Blues 15-13 and, more importantly, keep the defending champions' play-off hopes alive.
MacDonald scored all of the Crusaders points for a vital victory, however the visitors failed to take away an all-important bonus point that may come back to haunt them should impending results not go their way.
A dodgy TMO decision looked to have broken Crusaders' hearts, as Isaia Toeava was awarded a late try and Jimmy Gopperth's conversion put the Blues out in front with just under eight minutes to play.
But the Crusaders' determination and experience saw the ball worked back downfield for the set-up for which MacDonald obliged with a gentle chip through the posts.
The Blues started with a roar and hiss, showing their intentions early on as they looked to end their disappointing campaign on a high. The Crusaders were caught off-guard and nearly let in a try inside the opening minute as Gopperth raced away.
It would have been the perfect start for the Blues with a five-pointer under the posts, but Gopperth's final pass found a red and grey player instead of the familiar blue.
The hosts wouldn't stop there however. Every kick directed at them was run back with intent thanks to some excellent work by Rudi Wulf, who showed time and time again just what a tricky customer he can be on the counter-attack.
The visitors' were up to the task though and showed great commitment in the tackling department that disrupted the Blues' rhythm.
There were zip tries scored in the first half - something the Crusaders needed desperately to keep their play-off hopes alive, but that certainly couldn't be blamed for a lack of trying.
It was the best attack against the best defence. The Blues have scored four tries or more in every game they've played this season bar one, while the Crusaders have never once conceded four tries in all thirteen of their games. It was a game of chess, and checkmate to the Crusaders after heading into the break 6-3 ahead.
It could have been a six-point lead instead of three after the departing MacDonald missed a sitter, but made amends soon after with two successful penalties - one on the stroke of half-time.
Departing Blues fly-half Gopperth replied back with a penalty of his own in the solitary attempt handed to him. The Blues should feel relieved the gap wasn't more after a try-saving tackle by Wulf on Crusaders' pivot Stephen Brett prevented a certain score.
There were plenty more of that to come in the second as the Blues threw their bodies around like rag dolls in a bid to stop the charging Crusaders, who stepped up the tempo double-time after the break.
The hosts' over eagerness cost them another three points and a player in the bin for ten minutes after Tom Chamberlain was given his marching orders for killing the ball seven minutes into the second half.
However the Crusaders failed to capitalise after Thomas Waldrom knocked on with the tryline under his nose - this following a dubious TMO decision that ruled out a try to Michael Paterson deeming the grounding "inconclusive" when it was clear to see the lock got the ball down. Even referee Bryce Lawrence was puzzled.
Two lucky escapes inspired the fourteen-man Blues to get themselves back into this match and all of a sudden found themselves with an abundance of possession and plenty of territory to work with.
Another Gopperth penalty closed the gap to three points - his 100th of the season - once more and at 9-6, it was still anyone's ball game with the all-important bonus point and the game slipping away for the Crusaders.
MacDonald at least kept the Crusaders in front with his fourth successful penalty kick of the night in the 62nd minute, but fluffed a try-scoring opportunity soon after with a fumble of the pigskin ten metres out from the Blues' line.
Then moments later, at the other end of the field, Brett threw wild pass when attempting to field a kick ahead by Gopperth. Crusaders winger Jared Payne attempted to clean up the mess, but the ball emerged for Toeava to win the TMO's support in securing a try.
Although the TMO footage failed to add any clarity, the try was awarded and the Crusaders looked to be on their way out following Gopperth's conversion to give the Blues the lead for the first time in the game.
MacDonald had other ideas and when the time was right, he dropped back in the pocket and took his time slotting what could be the most important kick of his illustrious career.
The result moves the Crusaders to third place ahead of the Waratahs but the Hurricanes can push both teams down the pecking order if they score a bonus point victory over the Reds.
Man of the match: It took the first drop-goal of Leon MacDonald's long Super Rugby career to secure the win to keep Crusaders hopes alive. It was the perfect farewell for the durable MacDonald whose link with the Crusaders will end whenever this year's campaign is completed.
Pens: Gopperth 2
Pens: MacDonald 4
Blues: 15 Rudi Wulf, 14 Rene Ranger, 13 Anthony Tuitavake, 12 Isaia Toeava, 11 Joe Rokocoko, 10 Jimmy Gopperth, 9 Chris Smylie, 8 Jerome Kaino, 7 Tom Chamberlain, 6 Peter Saili, 5 Kurtis Haiu, 4 Jay Williams, 3 John Afoa, 2 Keven Mealamu (c), 1 Tony Woodcock.
Replacements: 16 Tom McCartney, 17 Tevita Mailau, 18 Dean Budd, 19 Andrew van der Heijden, 20 Grayson Hart, 21 Jamie Helleur, 22 Paul Williams.
Crusaders: 15 Leon MacDonald, 14 Jared Payne, 13 Tim Bateman, 12 Ryan Crotty, 11 Adam Whitelock, 10 Stephen Brett, 9 Andy Ellis, 8 Thomas Waldrom, 7 Richie McCaw (c), 6 Kieran Read, 5 Isaac Ross, 4 Michael Paterson, 3 Owen Franks,
2 Jason Macdonald, 1 Wyatt Crockett.
Replacements: 16 Daniel Perrin, 17 Bronson Murray, 18 Ross Filipo, 19 George Whitelock, 20 Kahn Fotuali'i, 21 Sean Maitland, 22 Hamish Gard.
Referee: Bryce Lawrence (New Zealand)
Touch judges: Vinny Munro (New Zealand), Jonathan White (New Zealand)
TMO: Chris Pollock (New Zealand)