PHILADELPHIA -- Jerome Williams pitched seven strong innings and Andres Blanco hit his first homer in over three years on Monday night as the Philadelphia Phillies beat the Seattle Mariners 4-1.

Williams, making his second start for Philadelphia since he was claimed off waivers from the Texas Rangers on Aug. 7, allowed one run and three hits to record his first decision with his new club. He struck out four and walked three.

Blanco, making a rare start at shortstop while Jimmy Rollins was given a night off, hit a three-run homer in the fifth inning. He last homered on July 1, 2011, while facing the Miami Marlins as a Texas Ranger.

It was also just his fourth homer in seven major league seasons. The Phillies are his fourth team, and he played in just his 19th game for them since his contract was selected from Triple-A Lehigh Valley on June 29.

Philadelphia reliever Ken Giles struck out the side while working out of a jam in the eighth, and Jonathan Papelbon pitched a scoreless ninth for his 29th save.

Left fielder Dustin Ackley drove in Seattle's only run with an eighth-inning double, as the Mariners fell for only the third time in 13 games.

Seattle starter Roenis Elias (9-10) lasted just four innings, allowing one run and three hits. He struck out four and walked six.

The Phillies broke on top courtesy of right fielder Marlon Byrd's RBI double in the third inning, but they left the bases loaded in the third and fourth against Elias.

Blanco added his three-run homer in the fifth, off reliever Dominic Leone. The blast came on a 1-1 pitch after a one-out double by left fielder Darin Ruf and a walk to third baseman Cody Asche.

NOTES: The Mariners optioned OF James Jones to Triple-A Tacoma to clear a roster spot for Monday's starter, LHP Roenis Elias. Jones hit .256 with 20 steals in 83 games for Seattle. ... Phillies OF/1B John Mayberry Jr., on the disabled list since July 21 with an inflamed left wrist, will begin a rehab assignment Tuesday at Triple-A Lehigh Valley. ... The Mariners last played in Philadelphia when they swept a three-game series at Veterans Stadium on June 3-5, 2003. The winning pitcher in the first of those games was Jamie Moyer, who later pitched for Philadelphia and is now a Phillies television broadcaster. ... Philadelphia SS Jimmy Rollins was given a day off. C Carlos Ruiz batted in Rollins' customary No. 2 spot in the lineup.