Lesley Vainikolo scored two crucial tries as Bradford edged into the Carnegie Challenge Cup quarter-finals at the expense of a determined Wakefield on Sunday afternoon.

The New Zealand winger, whose switch to rugby union with Gloucester is widely expected to be confirmed soon, crossed twice early on as the Bulls survived a tense encounter at rainswept Belle Vue.

The Wildcats put up strong resistance and kept the game tight through Paul White, but Matt Cook's first Bulls try 10 minutes from time settled the tie.

A week after Bradford's Millennium Magic engage Super League clash with Leeds ended in controversy over refereeing decisions, the Bulls were back in seemingly familiar territory within seven minutes of kick-off.

This time, however, a ruling was to go in their favour as Vainikolo was awarded the opening try after nearly three minutes of deliberations by the video official.

Vainikolo had outjumped Jason Demetriou to reach a Paul Deacon kick but there were suspicions of a knock-on against him and David Solomona before he finally gathered to touch down.

He was eventually given the benefit of the doubt and, after Deacon had converted, added a second in more typical fashion to reward the Bulls for their early supremacy.

The visitors twice went close through Ben Harris as they applied considerable pressure to the Wakefield line but they achieved only one more first-half breakthrough when James Evans got clear on the left.

Vainikolo was waiting in support in his usual manner and raced away to dive over.

Wakefield hit back to reduce the deficit to 10-4 at half-time after a brilliant piece of skill from Jamie Rooney.

The Wildcats stand-off gathered from a Jason Golden offload, moved into a gap and then flighted a perfect kick for White to score in the corner.

The video referee was again needed to determine whether Golden might have knocked on but 90 seconds were sufficient this time to reward Rooney's ingenuity.

Wakefield went on to finish the first half stronger but Brett Ferres wasted an opportunity when he kicked dead after a fresh set of six had just been awarded inside the Bulls' 10.

Bradford suffered a blow early in the second half when their replacement forward, and former Wakefield player, Chris Feather was carried off with a suspected broken leg after falling awkwardly in a challenge.

Full-back Michael Platt also left the field for treatment after bravely sliding into a collision with Ryan Atkins.

That came just moments after Platt had gone close to grabbing his side's third try with a blistering run that was halted just before the line by Sam Obst.

Wakefield were determined to fight hard and the Bulls struggled to assert any authority in a tight second half.

With 14 minutes remaining, Deacon tried to lift some of the tension but dragged his attempted drop goal wide.

It was not until the 70th minute that the Bulls were finally able to make the game safe.

Deacon created the chance with a quick break and when Luke George dropped the slippery ball from a Iestyn Harris kick, Cook had a simple job to touch down.

Deacon's conversion hit the upright but the Bulls could breathe much easier in the closing stages as Wakefield were left to rue their lack of a cutting edge.