Six penalties were the extent of the scoring in Treviso, with Dan Biggar kicking both for the visitors.

However, they paid for having to play three quarters of the game with 14 men, following the dismissal of Ian Evans for two yellow cards.

Playing into a strong wind before the break and a man light, the Ospreys trailed by nine points at the turnaround.

They dominated the final 40 minutes but had to settle for a losing bonus point as they launched the defence of their Pro12 crown.

A penalty for coming in from the side provided Treviso with an early opportunity to take the lead and despite his unconvincing kick that just about cleared the crossbar, Kristopher Burton was able to grab the first points of the night, the Italians going 3-0 up in the sixth minute.

The Ospreys were reduced to 14 just a couple of minutes later, Evans sent to the sin-bin for killing the ball on the floor after finding himself isolated.

Burton then punished the visitors for two offside decisions, leaving them 9-0 down after 14 minutes.

Bigger kicked the Ospreys’ first points after a rare attack resulted in a penalty but the Welsh province struggled in the conditions as Treviso dominated the territory.

However, the Italians’ progress was halted abruptly by a high tackle from Evans, back on the field just a matter of minutes, leaving the big second row on the receiving end of a second yellow card – and the Ospreys to play 50 minutes at a numerical disadvantage.

Burton then compounded the Ospreys’ woes, slotting his fourth penalty of the night before the break.

The visitors started the second half confidently and Biggar soon reduced the margin to six points when Treviso tighthead Ignacio Fernandez-Rouyet was penalised for not rolling away and shown a yellow card.

Ospreys centre Ashley Beck almost crossed the line but was adjudged to have been held up by Tommaso Iannone before Treviso were down to 14 again when replacement lock Dean Budd was yellow carded for a dangerous tackle on Richard Fussell.

Biggar then missed another kick on goal, his third of the night, as the reigning champions failed to find a cutting edge against dogged Italian defence.