Sweeney joined his new team Thursday, one day after being traded by Seattle. He wasn't in the starting lineup for the Phils' game at Florida, but he gives manager Charlie Manuel a reinforcement at first base with slugger Ryan Howard on the disabled list.
"Whatever Charlie asks me to do, I'll do it," said Sweeney, standing at his locker in his new uniform. "If he wants me to bunt, pinch run or play first base, I'll do everything in my power to be the best I can be."
Howard went on the disabled list Tuesday because of a sprained left ankle. Chase Utley and Shane Victorino are also sidelined, but despite a season-long wave of injuries, the Phillies went into their series finale at Florida only two games behind NL East leader Atlanta.
Sweeney broke into the majors in 1995, spent most of his career with Kansas City and has never reached the playoffs. The Phillies trade sent him from a last-place team to a team that has played in the World Series the past two years.
"To get the opportunity to be a small piece of an already great puzzle, it's a joy," he said. "I've always dreamed of playing in the playoffs and playing in meaningful games in September. I won't take for granted one second being here."
The 37-year-old Sweeney has been on the disabled list twice this season because of back trouble, but he said he's healthy now and able to play at first if needed.
"I'm ready to go," he said. "I'll just try to hold down the fort until big Ryan comes back, because he's one of the best players in baseball."
The Phillies are hoping Howard can return when eligible to come off the disabled list. At the time he was hurt, he led the NL with 81 RBIs.
Sweeney hit .263 with six homers in 30 games for Seattle this year. He's a career .298 hitter with 213 homers.
"He's a good hitter, a line-drive hitter who puts the ball in play and takes a lot of pride in his at-bats," Manuel said.
The Phillies acquired him for a player to be named later or cash considerations.