Sportal.co.nz 08.Mar.2013Getty Images
Leiua pounced on a pass by Adam Whitelock to score the crucial try and All Black first five-eighth Beauden Barrett slotted the conversion tos eal the dramatic win - their first of the Hurricanes' campaign.
Dan Carter had a chance to steal it for his side, who outscored the Hurricanes by four tries to two, with a late drop goal but sent his effort wide.
It left the Crusaders winless after two games in the tournament - the first time that has happened since 2004.
The Hurricanes led 12-7 at half-time thanks to Barrett's boot, but the Crusaders punished the home side for sloppy handling and passing int he second spell to score three tries to add to Ryan Crotty's 26th minute effort.
Corey Flynn, Israel Dagg and Carter all crossed in the second half with Carter converting them all.
Julian Savea capped off a good night with the Hurricanes' first try midway through the second spell, before Leiua and Barrett, who didn't miss a kick all night, provided the last-ditch heroics.
Barrett kicked all the Hurricanes points in the opening 40 minuts as the Crusaders' ill-discipline cost them.
But once again Mark Hammett's side were guilty of putting themselves under pressure with poor handling and poor passing.
Andre Taylor bombed a couple when his side were hot on attack, while Barrett put his outside backs in trouble with a couple of wayward passes - one deep inside his own half which saw captain Conrad Smith do his best impression of a slips catcher but to no avail.
The Franks brothers would have been happy though with the number of scrums that were set – and reset.
The Hurricanes largely held their own in the set piece but struggled with Dan Carter's short kick-offs.
The physical exchanges were as full-blooded as expected between two sides desperate to atone for poor starts to the season.
Robbie Fruean made plenty of impact in midfield for the Crusaders, although Blackadder would not have been happy to see him lose the ball in contact so much.
Savea made some telling runs down the left flank, bouncing off tackles left right and centre, but overall the Crusaders scrambled well in the first half to shut down the Hurricanes' opportunities.
But the visitors were able to pick apart the Hurricanes defence and it was the hard work of Crotty that resulted in the Crusaders' first try of the season in the 26th minute.
Barrett had already kicked his first penalty by this stage but the lead changed hands when Carter converted Crotty's effort which saw him brush past Barrett and Jason Eaton then slipped the tackle of Tim Bateman to score.
The Crusaders' ill-discipline, particularly at the breakdown, was costly in the final minutes of the half though as Barrett stepped up three times to knock over penalties to regain the lead for this team.
Dane Coles, playing in his 50th game alongside Victor Vito, was forced from the field early in the second half after hurting his ankle.
And three minutes later Crusaders hooker Flynn was being driven over for his side's second try and Carter's conversion saw the visitors regain the lead.
Another Taylor dropped ball resulted in a try for Dagg at the other end and capped off a miserable night for the Hurricanes fullback who was eventually replaced in the 62nd minute by James Marshall.
Savea got a well-deserved try in the 55th minute as the game opened up. A botched Crusaders lineout gave the Hurricanes possession and the ball was sent wide to the All Black's wing and he bounced off would-be tackles from Tom Marshall and Dagg to slide over.
Barrett's conversion got the Hurricanes back to within two points before another breakdown in their attack gifted the Crusaders yet another counter-attacking opportunity which ended with Carter scoring in the left corner and earning his side the four-try bonus point and a 28-19 lead.
But in a dramatic final 12 minutes Matt Todd was denied a try when TMO Glen Newman spotted a knock on by Kieran Read in the build-up.
Then Leiua pounced on an Adam Whitelock pass to score an intercept try and Barrett's conversion put the Hurricanes a point in front before Carter sent a drop goal wide.
Hurricanes 29 (Julian Savea, Alapati Leiua tries; Beauden Barett 2 con, 5 pen) Crusaders 28 (Ryan Crotty, Corey Flynn, Israel Dagg, Dan Carter tries; Carter 4 con) HT 12-7