Late tries from Wales internationals Justin Tipuric and Rhys Webb secured a 33-13 bonus-point win for the Ospreys over Treviso.
Treviso did claim some points in the first half courtesy of a single penalty for Jayden Hayward.
Ospreys went into the lead at half-time after two successful penalty kicks for Dan Biggar and a try for Eli Walker to give them a 3-11 lead.
The Italian side got back into the game in the second half with a try for Simone Ragusi and another penalty for Hayward but it was not enough to win them the game.
Ospreys fought back with three tries courtesy of Dan Evans, Justin Tipuric and Rhys Webb and another penalty for Biggar to win the game 13-33.
The Ospreys claimed their first penalty after only two minutes of the game had been played. However, the home side managed to hold out an early charge by the visitors to deny them any more points for now. Treviso equalised after 20 minutes with Hayward's penalty.
Referee Dudley Phillips grew impatient of the home side's constant infringements, which had contributed heavily to Ospreys lacks of points, and sent Enrico Bacchin to the sin-bin on 25 minutes. Biggar kicked the resulting penalty to put his side back in the lead.
On 39 minutes, Walker scored a crucial try for the visitors, stepping inside a handful of defenders to cross the line, meaning the Ospreys went into half time leading 3-11.
The Welsh side had Nicky Smith shown a yellow card in the first minute of the second half, with the prop paying the price for an earlier build-up of penalties. With the extra man advantage, Treviso put Ospreys under some serious pressure and when the ball was spun out wide to Ragusi, he crashed over in the corner for the try.
Just as Smith made his way back on to the field, Webb was also shown a yellow card for a high tackle on Ragusi, meaning the Ospreys remained with only 14 men on the pitch. Hayward kicked the penalty to put the home side in the lead for the first time.
However, back to full strength, the Ospreys started to work their magic and after Walker made the initial break, it was picked up by Evans who powered his way over the line for the try.
There was another penalty for Biggar before Tipuric put the ball down under the sticks. On 79 minutes, Webb grabbed the bonus point try to seal the 13-33 victory.
Pens: Hayward 2
Yellow Cards: Bacchin
Tries: Walker, Evans, Tipuric, Webb
Cons: Biggar 2
Pens: Biggar 3
Yellow Cards: Smith, Webb
Treviso: 15 Jayden Hayward, 14 Andrea Pratichetti, 13 Luca Morisi, 12 Enrico Bacchin, 11 Ludovico Nitoglia, 10 Sam Christie, 9 Edoardo Gori, 8 Mat Luamanu, 7 Francesco Minto, 6 Paul Derbyshire, 5 Corniel Van Zyl (c), 4 Marco Fuser, 3 Rupert Harden, 2 Davide Giazzon, 1 Matteo Zanusso
Replacements: 16 Albert Anae, 17 Romulo Acosta, 18 Matteo Muccignat, 19 Antonio Pavanello, 20 Meyer Swanepoel, 21 Nicola Cattina, 22 Simone Ragusi, 23 James Ambrosini
Ospreys: 15 Dan Evans, 14 Tom Grabham, 13 Jonathan Spratt, 12 Josh Matavesi, 11 Eli Walker, 10 Dan Biggar, 9 Rhys Webb, 8 Dan Baker, 7 Justin Tipuric, 6 Dan Lydiate, 5 Tyler Ardron, 4 Alun Wyn Jones (c), 3 Aaron Jarvis, 2 Scott Baldwin, 1 Ryan Bevington
Replacements: 16 Scott Otten, 17 Nicky Smith, 18 Dmitri Arhip, 19 Lloyd Peers, 20 James King, 21 Tom Habberfield, 22 Sam Davies, 23 Ben John
Referee: Dudley Phillips (Ireland)
Assistant Referees: Marius Mitrea (Italy), Simone Boaretto (Italy)
TMO: Carlo Damasco (Italy)