Marcus St Hilaire scored the match-winning try on his debut to send champions Bradford to the top of the engage Super League.

Lesley Vainikolo, who destroyed Hull with 10 tries in two games against them last season, tormented them again at Odsal with a try in each half, taking his remarkable tally to 114 in 108 appearances for the Bulls.

But injury-hit Hull made the champions work for their victory, which extended their unbeaten run to 18 matches and enabled them to leapfrog St Helens into pole position ahead of Saints' game at Huddersfield on Sunday.

Vainikolo, making only his second league appearance of the season, was a lurking menace throughout the first half but had to wait until seven minutes from the break to claim his first try.

Bradford had scored the first try after just 68 seconds but in between Hull enjoyed much of the play and deservedly got on the scoreboard just before the interval.

Without five regulars through injury, Hull gave a debut to 20-year-old forward Scott Wheeldon but, with experienced half-backs Paul Cooke and Richard Horne leading the way, they caused all sorts of problems for the champions.

Bradford, who brought in St Hilaire following the withdrawal of full-back Michael Withers with a shoulder injury, made a dream start after Hull's Great Britain forward Jamie Thackray lost the ball inside his own half.

Skipper Iestyn Harris, influential throughout, sensibly worked the ball out wide, where centre Karl Pryce, a player with the physical presence to match Vainikolo, barged his way over the line.

It looked like being the only score of the half as defences dominated but the Bulls broke away for Pryce to take another cut-out pass from Harris and feed his winger, who was unstoppable from such close range.

Paul Deacon kicked his first goal to make it 10-0 but Hull struck back immediately, courtesy of some smart work from substitute Peter Lupton.

First he palmed down a pass from Pryce to break up a dangerous attack and then produced a half-break which enabled Horne to put in a clever kick for centre Sid Domic to collect and touch down.

Danny Brough's touchline conversion cut the gap to just four points and keep the match finely balanced.

It took Vainikolo just four minutes of the second half to add to his phenomenal tally, taking another long pass from Harris to bounce off opposite number Motu Tony and claim his second try of the match.

But the "Volcano" turned from hero to villain five minutes later when a fumble on his own line allowed Kirk Dixon to score Hull's second try.

The ending might be considered fortuitous but some magnificent build-up justified the score, with Brough, Horne and Cooke handling superbly to give full-back Shaun Briscoe the position to put in the grubber kick.

Brough's second goal cut Bradford's lead to just 14-12 and set up a tense final quarter.

St Hilaire and substitute Matt Cook both spilled possession inside their own half to keep Hull on top and the Bulls were twice forced to drop out from their own posts.

The decisive score came 10 minutes from the end when St Hilaire, a surprise eve-of-season signing from Halifax, took Ben Harris' pass to crash over for the all-important try.

Even then, Hull had a chance to snatch a draw, with Briscoe spilling a pass from Lupton with the line beckoning and then knocking on in another promising position.