The Phillies placed pitcher Roy Oswalt on the 15-day disabled list on Friday night because of what they called lower back inflammation.
The move is retroactive to April 27, meaning Oswalt is eligible to return next Thursday.
To take his place, the Phillies recalled right-hander Scott Mathieson from Triple-A Lehigh Valley.
General manager Ruben Amaro Jr. said earlier Friday that Oswalt was feeling discomfort in his lower back and would see team physician Dr. Michael Ciccotti.
"Just some soreness but we're not going to take any chances," Amaro said.
Oswalt returned to the Phillies on Thursday after spending eight days with his family in tornado-ravaged Mississippi.
In mid-April, Oswalt came out of a game after hurting his lower back running the bases.
"I've been a little tight and it hasn't got any better," Oswalt said before the game. "I could probably pitch on Saturday but couldn't promise any results."
Amaro said before Friday night's game against the Atlanta Braves that Utley will play at least one inning in a game at Dunedin, Fla., on Saturday.
"It's a day-to-day process but he will be on the field to play," Amaro said. "He may play one inning, or more if he feels like it."