Ospreys survived a second-half Treviso comeback to earn a 38-17 bonus-point victory in their Heineken Cup opener.
Dan Biggar's trusted boot gave Ospreys the early breathing space they needed, as his hat-trick of penalties arrived only 15 minutes into the game.
Kris Burton kicked a penalty of his own just minutes before Eli Walker produced the first talking point of the game, evading four tackles as he ran inside from his wing to dot down next to the posts for the game's first try.
Both sides were reduced to 14 men as the Ospreys' Adam Jones and Treviso captain Antonio Pavanello were yellow carded for swapping punches, while the Italians were reduced even further with the sin-binning of Manoa Vosawai on his return to the side after a shoulder injury.
At 16-3 up on the half-time whistle, Ospreys took the game to Treviso with their second try five minutes into the second period. Hanno Dirksen went over in the corner, and with Biggar's second conversion of the night, Treviso were staring at a 23-3 deficit.
But that galvanised the Italians, as they came back with two tries; Vosawai making amends for his earlier indiscretion, before Luke McLean scored his first Heineken Cup try.
Both scores were converted by Burton, so with only a six-point advantage going into the final phase of the game, Ospreys had to pull something out the bag.
A fourth Biggar penalty eased the pressure, and with Simone Favaro seeing yellow on 70 minutes, Dirksen added his second try of the night, walking the ball over the line, before Ashley Beck secured a winning bonus point on the last play of the game.
Tries: Beck, Dirksen 2, Walker
Cons: Biggar 3
Pens: Biggar 4
Tries: McLean, Vosawai
Cons: Burton 2
Ospreys:15 Richard Fussell, 14 Hanno Dirksen, 13 Andrew Bishop, 12 Ashley Beck, 11 Eli Walker, 10 Dan Biggar, 9 Kahn Fotuali'i, 8 Jonathan Thomas, 7 Justin Tipuric, 6 Ryan Jones, 5 Ian Evans, 4 Alun Wyn Jones (c), 3 Adam Jones, 2 Richard Hibbard, 1 Ryan Bevington.
Replacements: 16 Matthew Dwyer, 17 Duncan Jones, 18 Aaron Jarvis, 19 George Stowers, 20 Sam Lewis, 21 Rhys Webb, 22 Matthew Morgan, 23 Tom Isaacs.
Treviso: 15 Luke McLean, 14 Ludovico Nitoglia, 13 Tommaso Benvenuti, 12 Alberto Sgarbi, 11 Tommaso Iannone, 10 Kristopher Burton, 9 Tobias Botes, 8 Manoa Vosawai, 7 Alessandro Zanni, 6 Simone Favaro, 5 Valerio Bernaḅ, 4 Antonio Pavanello (c), 3 Jacobus Roux, 2 Leonardo Ghiraldini, 1 Alberto De Marchi,
Replacements: 16 Enrico Ceccato, 17 Ignacio Fernandez-Rouyet, 18 Pedro Di Santo, 19 Francesco Minto, 20 Paul Derbyshire, 21 Robert Barbieri, 22 Fabio Semenzato, 23 Andrea Pratichetti.
Referee: Neil Paterson