PHILADELPHIA -- David Ortiz felt more comfortable circling the bases than playing first base.
Matt Clement pitched 6 2/3 solid innings, helping the AL East-leading Red Sox to their ninth win in 12 games. The Phillies have lost fourth straight after a 13-1 stretch.
Shane Victorino homered and Chase Utley drove in two runs for Philadelphia.
Playing his first game in the field this season because the designated hitter isn't used in interleague games at National League parks, Ortiz handled every chance without a problem. The first batter hit a sharp grounder right at him.
"It was a little weird out there," Ortiz said. "I have a 1.000 fielding percentage right now, but don't get too excited."
Clement (4-3) allowed three runs and five hits. He left after allowing consecutive two-out singles in the seventh. Keith Foulke entered and allowed Utley's two-run double into the right-field corner before striking out Bobby Abreu to preserve a two-run lead.
Mike Timlin pitched a scoreless eighth inning and Jonathan Papelbon finished for his major league-leading 15th save in as many chances.
Papelbon tweaked the heel of his foot fielding a bouncer for the first out of the inning, but stayed in and got the next two batters.
"He gave us all a scare," Red Sox manager Terry Francona said. "It looked ugly. But he was fine."
Jon Lieber (3-5) gave up five runs and seven hits in five innings for his first loss since April 21. Lieber had won his last three starts after going 0-4 with a 7.04 ERA in April.
"I sucked. That's the bottom line," Lieber said. "It's all about hitting spots and I didn't do a good job locating."
Lowell gave the Red Sox a 2-0 lead in the second inning with his fifth homer. Manny Ramirez started the inning with a long single. One out later, Lowell lofted a fly ball just inside the left-field foul pole.
Varitek hit one into the right-field seats to make it 3-0 in the fourth. Victorino's solo shot in the bottom half of the inning cut it to 3-1. But Ortiz put Boston ahead 5-1 with a two-run drive in the fifth. Ortiz ripped a 3-2 pitch into the second deck in right field for his 14th homer.
"I swing hard in case I hit it," Ortiz said. "It wasn't a bad pitch. It was a cutter coming in."
Lowell finished 3-for-3, raising his average to .331. A former All-Star, Lowell is coming off a miserable year in which he batted just .236 with eight homers and 58 RBI for Florida.
"He's done a great job," Francona said. "To say we're surprised is disrespectful. We're pleased."
A sellout crowd of 44,296 fans at Citizens Bank Park included hundreds of Red Sox fans. Chants of "Let's Go Red Sox" were heard throughout the game, though not nearly as prevalent as it was during Boston's trip to Philadelphia last year.
Boston leads the all-time series 14-12, including four straight wins in Philadelphia. ... The Red Sox have played eight straight errorless games and have made just 12 in 39 games, fewest in the majors. ... Phillies SS Jimmy Rollins broke a 2-for-28 slump with a two-out single in the seventh inning. ... Utley hooked a drive just outside the foul pole in right field three pitches before he doubled in two runs. ... Varitek has five hits in his last 23 at-bats, but three are homers. ... The Red Sox have won five straight interleague games on the road, dating to last season. ... Clement is 4-0 with a 2.20 ERA in his last four interleague starts.