Will Jordan scored two tries as the Crusaders recovered from an early deficit to edge the reigning champion Blues 21-14 and reach a 17th Super Rugby final in a match of rare intensity on Friday.
The Blues hammered away at the home try line for more than six minutes after the hooter looking for a converted try to force overtime but came away empty-handed as the Crusaders' defence held firm and kept them on track for a 13th title.
A try from Tom Christie set the Crusaders on their way as they fought back from 14-0 down in the 21st minute to guarantee a return to their home fortress next week to face the Waikato Chiefs or ACT Brumbies.
Neither the Chiefs nor Brumbies, who meet in the second semi-final on Saturday, will relish a trip to Christchurch, where the Crusaders are now unbeaten in 31 playoff matches over the three decades of Super Rugby.
"The Blues seriously hit us. Hell of a side. They were the champions and showed that tonight. We just managed to hold out," said All Blacks fullback Jordan.
"We knew the Blues weren't going to come down here and give it to us easy. It's finals footy, you find yourself in a bit of adversity and that's where you just try to take a step forward and embrace it."
The Blues, who had just scraped into the playoffs, made it clear that they would be looking to play an expansive game from the third minute when Beauden Barrett fired a cross-kick over to Caleb Clarke on the left wing.
The Crusaders snuffed out the danger that time but the visitors soon silenced the crowd when a raking AJ Ram kick resulted in a five-metre scrum and winger Mark Tele'a dived over in the corner for the opening try.
The home side were reduced to 14 men when Braydon Ennor was yellow carded for a dangerous tackle and centre Rieko Ioane went over under the posts to double the lead with a second try for the Blues.
The Crusaders cut the deficit soon after being returned to a full complement when openside flanker Christie forced his way over from close range after a series of his teammates had been repelled.
Blues prop Joshua Fusitu'a was sent to the sin bin for a high tackle on All Blacks captain Scott Barrett three minutes later and the crowd was back to full voice just before the break when Jordan crossed for a converted try to level up the scores.
The Blues spurned a straightforward shot at goal from a 51st minute penalty before knocking on from the tap and being pinged by the referee at the resultant scrum.
The Crusaders then laid siege to the Blues line, turning down several potential shots at goal in favour of kicks to touch before Jordan played tight forward to finally force the ball over the line with 10 minutes left on the clock.
Flyhalf Rivez Reihana slotted his third conversion to take the lead out to 21-14 and the visitors' woes deepened when number eight Hoskins Sotutu was sent to the sin bin minutes later, leaving them shorthanded for their late charge.
"Very tough. We started very well, we were able to play our game, then sort of let them back in and they were able to capitalise," said Blues captain Patrick Tuipulotu.
"We showed a lot of courage in that last eight minutes, but it just wasn't enough today."