"For two months, the Phillies have refused to put a timetable on Chase Utley's return. On Tuesday, the clock officially began.

Utley began a rehab assignment with Class A Clearwater on Tuesday night -- going 1-for-4 with a single and a strikeout. The move means he must be activated on the big league roster within 20 days.

Odds are, however, the All-Star second baseman, who has yet to play this season while nursing an injured knee, will be back before that.

Utley had 14 at-bats in extended spring training, where the looser set of rules allowed him to see more pitches and play just every other inning in the field.

With Clearwater, however, Utley will test his knee under similar conditions to what he'll face once he returns to the Phillies' lineup.

And that return, manager Charlie Manuel said, could have a major impact.

"One person can mean a lot," Manuel said. "That can have a lot of an effect on it, especially when you're the caliber player that Chase is. Yeah, we're going to get better when Chase comes back."

Through the first six weeks of the season, no team in the National League has gotten less offensive production from the second base position than the Phillies.

Utley's return to the 3 hole would provide a big bat in the middle of the lineup, and have the trickle-down effect of allowing Manuel to slide either Shane Victorino or Placido Polanco down in the order to spark a slugging bottom-half of the order.

"It will give us more things to do with our lineup, really," Manuel said. "It becomes stronger."

Utley was the designated hitter in Tuesday's game for the Threshers, who play again this morning. The team said Utley's presence in the lineup today would be a game-time decision."