The Phillies have endured injuries to both their ace and their closer this week, but they remain hopeful that both issues will be resolved by the weekend.

Cole Hamels, who suffered a mild sprain of his left ankle Tuesday, is set to throw a bullpen session tomorrow and evaluate his ability to make his scheduled start Monday in St. Louis. Brad Lidge, who has experienced inflammation in his right knee for most of the season, will also throw Friday. He played catch yesterday and reported no pain.

"That's a big day," Lidge said. "If it goes good, I'm going to be able to go that night."

If the session does not go well, the Phillies might place Lidge on the 15-day disabled list, retroactive to his last appearance Saturday in Miami. "There is no deadline" for a decision about whether to place him on the DL, "because we could backdate it," said general manager Ruben Amaro Jr. "The next 72 hours should let us know how he feels."

Hamels was unavailable for comment before last night's game, but Amaro and pitching coach Rich Dubee said they are still hopeful that the lefthander could start Monday. Amaro labeled Hamels' injury a "grade one sprain," the least serious of sprains.

"He's got some minor swelling in his ankle, but we're not sure what the status is on his next start," Amaro said. "[We're] still hopeful."

Dubee said that Hamels' bullpen session could be postponed until Saturday without delaying the scheduled start. As Hamels said Tuesday night, and Lidge reiterated yesterday, both pitchers are eager to resume their seasons and atone for disappointing performances in April.

"The hardest thing in the world is to watch a save," Lidge said.

Ruiz to rehab tonight

Carlos Ruiz (strained muscle, right side) took batting practice with the Phillies last night and will report to triple-A Lehigh Valley for a rehabilitation game today, according to Amaro, who declined to specify the length of the assignment. Ruiz is scheduled to catch today after suffering a minor setback Monday, when he experienced pain during batting practice and decided not to play in a minor-league game.

Madson steps up

Ryan Madson will handle most of the closing assignments until Lidge returns, and both Charlie Manuel and Dubee praised the 28-year-old righthander yesterday, saying that last year's pennant race and postseason helped Madson mature.

"I think Madson has the stuff, and I think he has the mentality to be a closer, yes I do," Manuel said. "The experience he's gotten over the years [has helped him], and his fastball has been real good since last August. . . . Getting it done builds confidence."

The manager said that when Lidge became unavailable, he never considered anyone but Madson as a substitute. Dubee said in March that Madson was Lidge's understudy, and reiterated that stance yesterday.

"He's got the potential to be" a closer, the coach said. "He's got a better understanding of his mechanics, and some of it is confidence. . . . I think he's grown into it. The World Series allowed his confidence to explode."

The righthander features a 96 m.p.h. fastball, offset by a change-up that is 20 m.p.h. slower. "That's a tough combination," Dubee said.

With Madson assuming responsibility for the ninth inning, Chad Durbin and Clay Condrey will share the eighth. Jack Taschner, Scott Eyre and J.A. Happ will continue to handle middle-inning duty.

Condrey and Durbin have pitched well for most of this season, and Durbin's 32/3 innings of relief after Hamels' injury Tuesday were crucial in sparing other relievers from being overworked. "That was enormous," Dubee said.