SEATTLE -- Daisuke Matsuzaka played the role of stopper Saturday night, helping put an end to the Red Sox's nine-game losing streak at Safeco Field. The right-hander delivered seven solid innings, leading Boston to a 4-3 victory over the Mariners.

The Boston starter allowed two runs, both on home runs, and struck out 10 batters on the night, equaling his Major League career high. It's the third time he's reached double-digit strikeouts, but the first since April 17 at Toronto.

"I thought he pitched really well," Boston manager Terry Francona said. "The two runs he gave up were two fastballs up and not located. Other than that, his stuff was good right from the first pitch of the game."

Matsuzaka allowed a solo home run to Adrian Beltre in the second to give Seattle a 1-0 advantage, but Boston turned the 1-0 deficit into a 2-1 lead. In the top of the fourth inning, Jason Varitek delivered a two-out double into the left-field corner off Jarrod Washburn scoring David Ortiz and Manny Ramirez. The Boston captain has been swinging a hot bat as of late, with nine hits in his last 24 at-bats (.375) with six RBIs.

"[Washburn] threw everything in that at-bat," Varitek said. "I was just trying to see the ball and I was able to keep one fair."

While the Boston offense was delivering the clutch hits, Matsuzaka was preventing them. Seattle loaded the bases with one out in the third, but the Boston right-hander wiggled off the hook by striking out Jose Guillen on three pitches, the last one a 96 mph fastball up and in that Guillen swung through. Matsuzaka retired Raul Ibanez on a routine fly ball to left field to escape the jam.

Seattle threatened again an inning later, putting runners on the corners with only one away. Matsuzaka kept the Mariners off the scoreboard by inducing an around-the-horn double play from Jose Lopez to keep Boston's one-run lead.

"Despite letting runners on base, I was able to battle through and prevent some runs from scoring," Dice-K said through an interpreter. "Being able to hold the batter with runners on base, that's a day in the life for me. That's really my true style of pitching."

The Red Sox's bats gave Matsuzaka some cushion to work with in the top of the sixth, scoring a pair of runs off Washburn. Kevin Youkilis doubled and scored on a Guillen throwing error. Ramirez followed with a run-scoring double, plating Ortiz with Boston's fourth run of the game.

Working with a three-run lead, Matsuzaka created some more trouble for himself in the bottom of the frame by hitting Ibanez and walking Beltre to lead off the sixth inning. Once again, nothing would come of the Seattle threat as Dice-K retired the next three batters in order, striking out two.

The Boston bullpen made it interesting, as Eric Gagne allowed a run in the eighth inning to cut the Boston lead to one run. In the ninth inning, closer Jonathan Papelbon walked a pair before retiring Beltre on a foul popup to secure the victory and end the Red Sox's losing streak in Seattle.

"As a team, we haven't been able to win here in Seattle this season," Matsuzaka added. "I'm very happy we were able to win today."

Matsuzaka's 10-strikeout performance brought his season total to 152, second all-time on the Red Sox's rookie strikeout list. Dice-K moved past Dutch Leonard and Dick Radatz, who both struck out 144 in their rookie campaigns. Ken Brett set the franchise's rookie record of 155 strikeouts in 1970.