The Crusaders eked out a third-successive narrow win, beating the Bulls 16-13 in Christchurch on Friday night to cling to their hopes of a Super 14 rugby title defence.

Following a first half when the Crusaders played an expansive brand of rugby, the match turned on its head after the break with the error-prone hosts forced into a welter of defending.

Once again their competition-best defence prevailed, as it did in gutsy four-point defeats of the Waratahs and Stormers in recent weeks.

It leaves the Bulls reflecting on a second straight defeat. They were unbeaten and led the competition before last weekend's 36-12 hammering from the Highlanders.

They scored two tries to one - both to winger Akona Ndungane - but five-eighth Morne Steyn missed both conversions from the right touchline while opposite number Stephen Brett had an unusually-accurate night at AMI Stadium, landing three-from-three and a dropped goal.

Their only try was a fifth-minute effort to lock Isaac Ross although they deserved more in a first half they dominated.

They spun the ball successfully from deep and backs and forwards off-loaded at will, forcing the Bulls to dig deep defensively.

It was the visitors who kept the ball in hand after halftime and they deserved the bonus point that lifts them - at least temporarily - one point ahead of the fifth-placed Crusaders, who have a bye next week.

A curious aspect of the match is that both teams struggled to field high kicks, the ball being left to bounce an inordinate number of times.

That led to the first try of the night, in the fifth minute when an innocuous Crusaders kick was fielded by leaping winger Colin Slade, who produced an overhead pass in the same motion. He brilliantly found rangy lock Ross, who strode over next to the uprights.

Brett converted and extended the lead with a 15th-minute penalty but their 10-point advantage was halved when Ndungane crossed in the right corner.

It came when the visitors' most incisive player - centre Wynand Olivier, in his 50th Super rugby match- busted through opposite number Tim Batemen.

Brett put the Crusaders 13-5 up with a simple dropped goal soon after halftime but the Olivier-Ndungane combination was at it again with 25 minutes remaining.

This time it was a pinpoint cut out pass from the midfielder, giving the wing an unimpeded sprint to the corner.

A Brett penalty following replacement flanker Pedrie Wannenburg's high tackle on Bateman had the hosts back in front and they held on for the final 15 minutes as both sides committed the mistakes that reflected their levels of fatigue.

Brought to you by AAP © 2024 AAP