TORONTO – Mike Mussina won for the first time this season as the Yankees beat the Toronto Blue Jays 4-3 last night.

Mussina (1-1) allowed three runs and 10 hits in 5 1/3 innings, striking out five and walking one.

The 36-year-old right-hander escaped jams in the third and fourth innings by inducing double play grounders. Relievers Buddy Groom and Frankie Rodriguez bailed him out in the sixth, getting out of a one-out, two-on jam.

Mariano Rivera allowed two runners in the ninth but got his third save in five chances.

Bernie Williams had two hits and an RBI for the Yankees, who swept the two-game series. New York arrived in Toronto having lost five of six games, and were tied with Tampa Bay for last place in the AL East at 5-9.

The Yankees spoiled the home debut of rookie left-hander Gustavo Chacin (3-1), who won his first three starts. Chacin allowed four runs and six hits in six innings.

Toronto loaded the bases in the third, but Corey Koskie hit a grounder to Mussina, who started a 1-2-3 double play. Toronto’s Alex Rios also hit an inning-inning double play in the fourth.

Williams led off the fourth with a single and scored on Gary Sheffield’s RBI double. Hideki Matsui followed with a sacrifice fly for a 2-0 lead.

Chacin walked Jorge Posada to lead off the fifth and allowed a single to Tino Martinez before Rey Sanchez advanced the runners with a sacrifice. Derek Jeter followed with a sacrifice fly and Williams added an RBI single to make it 4-0.

The Blue Jays rallied with three runs in the fifth when Orlando Hudson, John McDonald, and Frank Catalanotto led off with three straight singles. Catalanotto’s scored Hudson. Shea Hillenbrand and Vernon Wells added RBI singles off Mussina, cutting the lead to 4-3.

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YANKEES PLACE SIERRA ON DL

The Yankees placed designated hitter Ruben Sierra on the 15-day disabled list yesterday with what might be a slight tear of his right biceps. Sierra will have an MRI exam today to determine whether he has a tear. He was hurt while swinging at a changeup during Wednesday’s game in Toronto.

“I felt a little pop in there. The next pitch I got a hit but felt pain,” he said.

Sierra doubled on the next pitch but was removed from the game before his next at-bat. His swollen arm was wrapped yesterday as the Yankees took the field for the second game of their series against the Blue Jays.

“He’s got discoloration there. Hopefully, it’s not too bad,” manager Joe Torre said. “With the blood in there, there’s obviously something going on. It’s going to be 10 or 12 days anyway.”