Bath booked their place in the Almin Challenge Cup quarter-finals with victory over Agen while Grenoble upset Stade Franšais and Worcester smashed Rovigo.
Elsewhere, Tom Varndell responded to his England omission with the fastest hat-trick in Challenge Cup history as Wasps also qualified for the play-offs.
Calvisano 34 - 20 Bucuresti
London Welsh 62 - 5 Cavalieri Prato
Rovigo 17 - 80 Worcester Warriors
Bath 19 - 16 Agen
Bizkaia Gernika 15-50 Perpignan
London Wasps 71-7 Mogliano
Grenoble 15-9 Stade Franšais
Wasps ran 11 tries past Mogliano - including three in just 13 minutes for Tom Varndell and two for scrum-half Charlie Davies - to open a six-point lead over Bayonne in Pool 3 with only one round of games remaining.
Bath extended their unbeaten record in this tournament to14-games when Tom Heathcote's penalty settled a tense clash at the Recreation Ground against Agen. Paul James grabbed Bath's only try for a 13-9 lead at half-time but the hosts were made to work hard after Heathcote missed a string of kicks before landing two decisive penalties.
Calvisano claimed their first win of the European season against Bucuresti.
Worcester ran 12 tries past Rovigo in Italy with Josh Drauniniu scoring a hat-trick. Nikki Walker, Blair Cowan and Max Stelling also all crossed twice.
Perpignan and Worcester are level on points at the top of Pool Two after the Catalans thumped Bizkaia Gernika.
London Welsh scored nine tries at the Kassam Stadium for their first home European win as they did the double over Italian minnows Cavalieri Prato.
Stade Franšais missed out on early qualification for the quarter finals as they lost their unbeaten record in a hard-fought but try-less affair against Grenoble .
A losing bonus point leaves the Parisians five points clear of London Welsh, meaning one more point in next week's clash with English club will be enough to secure a place in the play-offs. Four penalties from fly-half Clement Darbo and one from Nicolas Laharrague saw Grenoble home, with three penalties from full back Jerome Porical all Stade could muster in return.