Newport Gwent Dragons paid a high price for indiscipline as Treviso ran in five tries and picked up a bonus in the Robo Direct Pro 12.
They conceded 12 points either side of half time when Will Harries was off the field for a deliberate knock on.
And the Dragons were mounting a fight-back until arries picked up a second yellow on the hour and was dismissed.
Tom Prydie scored all the Dragons' points with a try, conversion and two penalties.
Dragons had a dream start on a sunny north Italian afternoon when full-back Prydie slotted a penalty after an infringement on the ground.
But Treviso, who started the match one point ahead of the Welsh region in the Pro 12 table, quickly established a territorial advantage.
And they were rewarded when scrum half Edoardo Gori took advantage of some confusion in the Dragons defence to dive over wide on the right in the ninth minute, fly half Alberto Di Barnardo adding the extra points.
The stand off was on target again with a penalty two minutes later, before Prydie reduced the arrears with his second successful kick.
The Italian team showed confidence in their pack when opting to kick to touch from inside the Dragons 22 in the 18th minute, but the Dragons defended the resulting lineout well.
The Dragons had a number of kicks charged down, and were punished in the 25th minute when Dan Evans opted to kick in the Treviso 22.
The charged-down ball bounced kindly for the home team, with lock Corniel van Zyl leading a 50 metre charge before sending a well-timed pass to Christian Loamanu who crossed wide out on the left. Di Barnardo's conversion attempt failed.
Treviso's dominance paid off when Dragons wing Will Harries was yellow carded for a deliberate knock-on, and they took advantage of the extra man to work Luke McLean over on the left for their third try.
The yellow card proved to be exceptionally expensive as Loamanu pounced for his second try and a bonus point in the first minute after the restart. Di Barnardo added the conversion.
Back to a full complement of players, the Dragons hit back when Tom Brown led a charge up the middle before Tom Prydie was worked over on the left. The full back converted his own try.
But any hopes of a Dragons comeback disappeared when Harries picked up a second yellow card on the hour and was sent off.
Treviso took advantage when replacement Tobias Botes burst clear from half way and shrugged off the weak tackle of Chavhanga before crossing midway out on the right.
Dragons: Tom Prydie, Will Harries, Pat Leach, Ashley Smith, Tonderai Chavhanga, Dan Evans, Jonathan Evans, Phil Price, Hugh Gustafson, Dan Way, Adam Jones, Rob Sidoli, Lewis Evans (capt), Nic Cudd, Tom Brown.
Replacements: Steve Jones, Owen Evans, Nathan Buck, Ian Nimmo, Ieuan Jones, Wayne Evans, Lewis Robling, Jack Dixon.
Treviso: Brendan Williams, Luke McLean, Christian Loamanu, Alberto Sgarbi, Ludovico Nitoglia, Alberto Di Bernardo, Edoardo Gori, Manoa Vosawai, Alessandro Zanni, Simone Favaro, Corniel Van Zyl, Antonio Pavanello, Lorenzo Cittadini, Leonardo Ghiraldini, Alberto De Marchi
Replacements: Enrico Ceccato, Michele Rizzo, Ignacio Fernandez-Rouyet, Valerio Bernabò, Francesco Minto, Paul Derbyshire, Tobias Botes, Luca Morisi
Referee: David Wilkinson (IRFU)
Assistant Referees: Stefano Penne, Stefano Marrama (both FIR)
Citing Commissioner: Maurizio Vancini (FIR)
TMO: Alan Falzone (FIR)