Last-gasp penalty clinches thriller for Crusaders

James O'Connor celebrates with the Crusaders after kicking their winning penalty against the Blues tonight. Photo: Getty Images

A last-play penalty goal to James O'Connor has given the Crusaders a thrilling 25-22 win over the Blues, preserving their top spot on the Super Rugby Pacific ladder.

The decisive play was due to a huge scrum effort from the Crusaders' pack tonight, which gave referee Nic Berry no option but to award a penalty 40 metres out.

O'Connor, a former Wallaby, had knocked over a penalty from almost exactly the same spot nine minutes earlier, and again was dead on target to win a game that had been played in difficult conditions thanks to steady rain in Christchurch.

Crusaders prop Tamaiti Williams opened the scoring with a well-taken try inside the first few minutes.

However, the Auckland-based Blues shook off the early setback to dominate territory and possession for most of the rest of the half, denied first by the TMO and then scoring through lock Josh Beehre.

The game was looking to be locked up at half-time, but the Crusaders cashed in on being handed the ball in the Blues' 22 as time expired, a lovely pass from David Havili sending Will Jordan over.

Christian Lio-Willie barged over from a lineout after the break to open up a two-try lead for the Crusaders, but the Blues then went back to their possession-based game in the wet conditions, eventually creating an opportunity after 64 minutes.

First Hoskins' Sotutu did it himself in the 58th minute, then his outrageous behind the back pass for AJ Lam to score made it 19-all.

Beauden Barrett, who had been controlling the match very well with his kicking, then knocked through a penalty to give the Blues their only lead of the game.

However, up stepped O'Connor to provide the final, dramatic act.

The win preserves the Crusaders' lead at the top of the Super Rugby Pacific standings.

They now head to Dunedin next weekend for match against the Highlanders.

The Blues are now in must-win territory as they try to defend their title.

They sit in eighth and face a tough challenge in Brisbane next weekend against the Reds.