London Wasps laboured to a 32-11 unconvincing victory over Rovigo but it was enough to stay in control of Amlin Challenge Cup Pool Three.
Sam Jones and Elliot Daly scored in the first half but it was not until Ryan Davis and Richard Haughton touched down in the final three minutes that Wasps clinched the bonus point.
That extra point ensured Wasps will reach the quarter finals with victory over Bordeaux-Begles next Sunday.
Rovigo had only won once in the last six seasons in Europe, yet Wasps led by just 15-11 eight minutes from time. This was despite a promising start to the game which saw Haughton and Davis make threatening runs and the Wasps pack attempt a drive from a close-range lineout.
But the Italians took the lead against the run of play through a Davide Duca penalty, and although Jones and Daly crossed before the break Wasps could not shake off Rovigo's dogged determination. Duca's second penalty meant that there were just six points between the teams at half-time and when wing Samuele Pace scored an opportunist try the deficit was down to one.
However Duca was off target with the conversion, and his wastefulness from a pair of missed penalties proved crucial as Davis scored a fine solo try which, when added to his two penalties, finally gave Wasps some breathing space with three minutes to play.
With dense fog descending on the Stadio Mario Battaglini Wasps threw caution to the wind to go for the bonus point. England call-up Joe Simpson had one dangerous break, but it was not until the final play of the game that Haughton forced his way over to ensure a maximum haul.