After an extra-innings victory Saturday, USC needed a strong performance from senior starting pitcher Kevin Couture to keep the momentum going Sunday.

Unfortunately for the Trojans, Couture was not sharp, and the No. 18 Oregon Ducks won the series finale, 8-4, to take two of three.

Couture struggled out of the gate, allowing two runs in the first inning to put the Trojans behind, 2-0.

USC’s (17-22, 3-12 Pac-10) bats responded with four runs in the top of the third. Junior infielder Joe De Pinto scored on a wild pitch with the bases loaded to make it 2-1.

Two batters later, senior infielder Keith Castillo hit a two-run single to left. Sophomore catcher Kevin Roundtree followed with an RBI groundout, giving the Trojans a 4-2 lead.

But Couture continued to struggle in the bottom of the third, when he loaded the bases with nobody out to start the inning. After designated hitter Ryan Hambright struck out, Couture served up a grand slam to Oregon third baseman J.J. Altobelli.

The next batter doubled before Couture was removed. He lasted just two and one-third innings, giving up six earned runs on 10 hits to take the loss and fall to 2-2.

USC’s offense went silent after the third, mustering just three singles and a double during the final six innings of play.

Oregon’s Zack Thornton pitched seven shutout innings in relief of starter Alex Keudell, who was charged with all four USC runs.

On Saturday, the Trojans trailed 2-0 after two innings of play, but scored one in the third and one in the seventh to tie the game.

They went ahead with two runs in the top of the ninth inning, but the Ducks tied it with two in the bottom of the frame.

USC was able to manufacture a run in the top of the 10th inning to take the lead. Freshman outfielder Alex Glenn walked with two outs, stole second, advanced to third on a wild pitch and scored on senior outfielder Mike O’Neill’s single.

Junior reliever Chris Mezger put two men on with one out in the bottom of the inning before shutting the door to earn the 5-4 victory. He improved to 4-0 on the season.

Oregon routed USC on Friday, scoring six runs in the first three innings on the way to a 12-2 win.

Sophomore starting pitcher Andrew Triggs allowed seven runs, four earned, in five innings. He also allowed 11 hits and walked three Oregon batters.

Ducks starter Tyler Anderson struck out 10 Trojans during his six and two-thirds innings of work.

The Trojans remain in last place in the Pac-10 and have a lot of ground to make up with just 12 conference games remaining.

USC’s next game is Tuesday at UC Santa Barbara before the team returns for three games at home against No. 17 Arizona.