A brave Crusaders defensive effort was finally undone by the Brumbies 18-16 tonight in a thrilling finish thanks to a Stirling Mortlock conversion after the final hooter.

The Crusaders had defended their line heroically in the final 10 minutes in attempting to hold on to their 16-11 lead, but a try to fullback Mark Gerrard in the final minute and Mortlock's conversion clinched it for the Brumbies, who also came back from the dead in their round-one victory over the Highlanders in Dunedin last weekend.

It was tough on the Crusaders, who looked to have done enough to have won the match, despite surviving on scraps of possession and territory and missing injured All Blacks Richie McCaw, Brad Thorn and Leon MacDonald.

They put only one attacking move together in the Brumbies' 22m in the second half - and scored from it after Colin Slade charged down a clearance and the ball went to Ross Filipo via Casey Laualala, with the lock dotting down in the corner.

Centre Laulala scored the Crusaders other try in the first half when intercepting a George Smith reverse pass and running 45m to dive over.

The Brumbies seemed rattled by the Crusaders rush defense and trailed the whole match until Mortlock's late kick, which was well taken on the angle from the right-hand side of the field.

However, the Crusaders also made many errors, and couldn't hold on to the ball to put any attacking pressure on the Brumbies.

Slade began the scoring for the Crusaders in the seventh minute when kicking a penalty following a scrum infringement from the Brumbies.

The Brumbies followed suit in the 17th minute when Gerrard kicked a penalty after George Whitelock was off-side in a ruck.

But the Crusaders hit straight back with Laulala's try, the centre in a try-scoring mood after his double in the victory over the Chiefs at AMI Stadium last weekend.

The Crusaders survived a scare when flanker Smith charged down an Andy Ellis clearance but the ball went dead. However, Smith was in the action again when setting up the first try for the Brumbies after the Crusaders missed his run near a ruck and he passed outside for Christian Lealiifano to score to even things up at 8-8.

The Crusaders hit back just before halftime when Stephen Brett took over the kicking duties and put the Crusaders ahead 11-8 with a penalty.

Blackadder's team would have been satisfied to go to the break with a three-point advantage.

While they hadn't created a lot on attack, their aggressive defence had the Brumbies rattled and they were taking advantage of the Australians' mistakes.

Brett saved the Crusaders within 10 minutes of the re-start when scrambling well and kicking the ball away from the finger-tips of wing Clyde Rathbone.

Mortlock levelled the scores 11-11 in the 56th minute when Isaac Ross was offside at a ruck.

But the Crusaders hit back straight away when lock Filipo scored in the corner following Slade's charge-down. Brett missed the conversion and the score was 16-11.

Mortlock missed the chance to narrow the gap with a penalty after the Crusaders were offside from a defensive scrum.

The Crusaders survived several Brumbies raids close to their line but the weight of territory and possession told and Gerrard eventually scored, stepping inside a stretched Crusaders line, with Mortlock kicking the conversion after the hooter to win it.

Head coach Todd Blackadder paid credit to his team's defence and acknowledged that things didn't really go their way tonight. He said: "I'm really proud of the boys. It was unfortunate at the finish but you couldn't fault their endeavour."

The Crusaders next match is against the Hurricanes on Friday night at AMI Stadium.

Brumbies - Tries: Lealiifano, Gerrard. Pens: Gerrard, Mortlock. Con: Mortlock.

Crusaders - Tries: Laulala, Filipo. Pens: Slade, Brett.

HT: Crusaders 11-8.

1. Wyatt Crockett (17. Bronson Murray 56th minute)
2. Corey Flynn (16. Jason Macdonald 27th minute)
3. Ben Franks
4. Isaac Ross
5. Ross Filipo (18. Michael Paterson 60th minute)
6. Kieran Read (c)
7. George Whitelock
8. Thomas Waldrom
9. Andy Ellis (20. Kahn Fotuali'i 50th minute)
10. Colin Slade
11. Kade Poki (22. Adam Whitelock 69th minute)
12. Tim Bateman
13. Casey Laulala
14. Jared Payne
15. Stephen Brett

Reserves not used:
19. Nasi Manu
21. Ryan Crotty