WASPS can look forward to a home quarter-final in the Amlin Challenge Cup after finishing off a highly impressive pool phase with a victory at Newport-Gwent Dragons.

It wasn't pretty, it was never going to be this side of the Severn Bridge on a freezing January night, but the black and golds clawed their way over the line 20-19 to finish Pool Three unblemished with five wins and a draw.

A penalty try plus a clever score from Nick Robinson did the job for them, although their stubborn-bordering-on-belligerent attitude counted in their favour just as much as Rodney Parade became a cauldron of hostility in the final stages.

It was no less than they expected but, by hook or by crook, Wasps escaped with the result they wanted and when the competition comes around again in April that could make all the difference.

Despite the hard-talking during the week and the intent signalled by Dai Young's team selection, Wasps were slow to warm up and the most interesting thing about the first quarter was the form of Billy Vunipola after it emerged this week that he had signed for Saracens in controversial circumstances.

But, to the giant number eight's credit, he didn't appear distracted by the issue and certainly wasn't work shy on the pitch as he carried the fight to the hosts with a number of muscular surges.

Robinson also looked in good form early on but it was Dragons who got their noses in front - first from a Tom Prydie penalty after 13 minutes and then, after Robinson had replied in kind, with the game's first try after 26 minutes.

Wasps caused it when they coughed up the ball just outside their own 22 and despite a magnificent tap-tackle from Sam Jones, the Welshmen capitalised with fly half Dan Evans going over.

Prydie added the extras to make it 10-3, but the lead was short-lived.

Robinson's second penalty cut the gap and after he hit an upright with a third attempt and the TMO ruled against Wasps after a mad scramble for the ball in Dragons' in-goal area following the umpteenth charge down, the black and golds got their reward with a penalty try from the resulting scrum.

Robinson converted to put them 13-10 up, but neither side had done enough to lead at half time and neither did with Prydie landing another kick to make it 13-13.

That was still the score when Vunipola limped out of the action after crashing into the Dragons' line once too often with 47 minutes gone, but Wasps used the injury to freshen things up with James Cannon, Joe Simpson and Thomas Rhys Thomas all coming on.

Stephen Jones followed ten minutes later and gradually, minute by minute, Wasps inched to victory.

Robinson's final contribution had been to end extended Wasps pressure with their second try when he successfully chased his own grubber, and his conversion stretched the lead to 20-16.

It proved to be just enough.

Dragons cut the gap to one point with a long-range penalty after 71 minutes and missed a string of kicks either side of that. They also threatened to run home match-winning scores twice in the final moments of the match as the partisan crowd reached a crescendo of noise.

But last-ditch tackles and brutal defence avoided catastrophe for the visitors, who dust themselves down and probably emerge stronger for the experience.