The Crusaders have kept their Super Rugby Pacific playoff chances alive with the upset of the season, the defending champions beating the Auckland-based Blues 29-27.
The Crusaders came into Saturday's match with only two wins from 12 games, in 11th place on the 12-team table.
The Blues had lost only once and were trying to return to the top with one round left in the regular season.
But after a woeful campaign by the 12-time champions Crusaders - the worst in their history - they finally produced a performance reminiscent of the past. The win could lift them as high as ninth, within reach of the top-eight playoff zone, ahead of their last regular-season match against Moana Pasifika.
"I think (a performance like this) has been there, but we haven't capitalised on opportunities," said captain Codie Taylor, who spent much of a physical match bloodied from a head gash.
"We knew what we were up against with the Blues, a real class side. You could see they deserve to be where they are. But there was a lot of chat about the boys who have been before us and what this meant to them, and it was good to get a result."
The match was close but for a period between the 22nd and 35th minutes when Blues prop Ofa Tu'ungafasi scored two tries to give his team a 15-7 lead.
But the Crusaders scored a vital try through winger Chay Fihaki right on halftime and cut the deficit at the break to three points.
That set up a thrilling second half in which the Crusaders captured the lead for the first time in more than 40 minutes after a try by scrumhalf Noah Hotham. That gave them a 26-22 advantage, which became 29-22 after a penalty from Fihaki in the 67th.
The Blues rallied with a try by winger AJ Lam, but flyhalf Harry Plummer missed the sideline conversion and the Crusaders clung to their two-point margin to the joy of a capacity crowd.
The loss sends a playoff warning to the Blues, who looked formidable while building an 11-1 record. While they looked solid in the first half, they lost their shape and patience in the second. They were best when they stacked together phases, but as tension built they played more individually and the Crusaders capitalised.