SEATTLE -- Boston's Daisuke Matsuzaka left before the bottom of the fifth inning because of an apparent injury to his lower back in the Seattle Mariners' 4-3 victory over the Red Sox on Tuesday night.
The 11th Red Sox pitcher to win his first eight decisions in a season gave up three runs -- two earned -- and four hits in four innings. Then, after two seemingly routine warmup pitches before the bottom of the fifth, he appeared to briefly grab his lower back.
Matsuzaka, who struck out two, was trying to join Josh Beckett from last season in starting the season 9-0.
Roger Clemens has the best start in Red Sox history, 14-0 in 1986.
Jose Lopez lined a single past diving third baseman Mike Lowell to score Wladimir Balentien with the game-winning run in the ninth as the Mariners ended a season-high seven-game losing streak.
Manny Ramirez hit his 499th home run for the Red Sox.
J.J. Putz (2-2) pitched a scoreless top of the ninth for the Mariners.