Treviso completed a Pr012 double against Newport Gwent Dragons in a thrilling, if error-strewn, encounter at Rodney Parade.
The visitors, who beat the Dragons 50-24 in October, won by the slenderest of margins despite being reduced to 13 men late in the game.
Aled Brew (twice), Toby Faletau and Adam Hughes scored for the Dragons.
Alessandro Zanni, Luke McLean, star fly-half Kris Burton and centre Alberto Sgarbi went over for the visitors.
Burton also added two conversions, two penalties and a crucial drop-goal for a full card of scores in his 18-point haul.
Defeat underlined the Dragons' role as Wales' poor relations in the competition, as well as ending their remote hopes of securing a Heineken Cup place next season.
Treviso's success came less than two weeks after the 41-10 defeat inflicted by the Ospreys on their last visit to Wales.
On that occasion they were a clear second-best to a team bidding to be in the play-offs.
But on Friday the Italian side matched their opponents and underlined their credentials as a team to be respected.
The Dragons go to Liberty Stadium next Friday, when the hosts will be marking Wales wing legend Shane Williams's forthcoming retirement.
Darren Edwards's side showed some fine attacking touches as wing Aled Brew's opening try demonstrated.
The scores were tied 3-3 via penalties from fly-half opponents Lewis Robling and Burton when Brew was set free on the left.
But when Tonderai Chavhanga was stripped of the ball in a tackle, Treviso reacted swiftly to send openside flanker Zanni over.
Burton and Robling exchanged penalties again before Brew intercepted and raced away only for full-back McLean to respond at the other end.
Wales star Faletau's try in the 50th minute was converted by Hughes.
But back came the visitors through Burton, who followed up his own charge down to score.
He missed the conversion, but knocked over a 67th-minute drop-goal moments after home flanker Lewis Evans was sin-binned.
Treviso prop Michele Riizzo followed Evans three minutes later after Faletau threatened to break away.
Having seen Brew steal an intercept, the Dragons could only watch as Sgarbi returned the compliment, Burton adding the extra points.
When replacement Fabio Semenzato was sin-binned with five minutes remaing, the visitors were down to 13 men.
The Dragons took advantage through Hughes with less than three minutes remaining, the centre also converting.
Despite a desperate last wave of attacks, the Dragons had to be satisfied with losing and four-try bonus points while Treviso took the bonus-point win.
Newport Gwent Dragons: Will Harries, Tonderai Chavhanga, Adam Hughes, Ashley Smith, Aled Brew; Lewis Robling, Joe Bedford; Nathan Williams, Sam Parry, Nathan Buck, Luke Charteris (c), Rob Sidoli, Danny Lydiate, Toby Faletau, Lewis Evans.
Replacements: Jason Tovey for Robling (68), Phil Price for N Williams (54), Dan Way for Buck (74), Andrew Coombs for S Morgan (48).
Not Used: Steve Jones, Tom Brown, Wayne Evans, Hallam Amos.
Sin Bin: L Evans (66).
Treviso: Luke McLean; Ludovico Nitoglia, Tommaso Iannone, Alberto Sgarbi, Brendan Williams; Kris Burton, Edoardo Gori; Michele Rizzo, Franco Sbaraglini, Lorenzo Cittadini, Antonio Pavanello, Cornelius van Zyl, Marco Filippucci, Robert Barbieri, Alessandro Zanni.
Replacements: Muccignat for Williams (72), Vidal for Sbaraglini (50), Minto for A Pavanello (67), Bernabo for Filippucci (74).
Not Used: Ignacio Fernandez Rouyet, Simon Picone, Fabio Semenzato, Alberto Di Bernardo.
Sin Bin: Rizzo (69), Semenzato (75).
Referee: James Matthews (SRU)
Assistant Referees: Sean Brickell and Chris Williams (Both WRU)
Citing Commissioner: Denis Jones (WRU)