ATLANTA - Cliff Lee's stay on the disabled list may not be much longer than the mandated 15 days.

Lee threw what he termed a pain-free bullpen session Wednesday at Turner Field, taking the next step in his recovery from a strained left side. He is eligible to be activated Friday, but it won't happen then. Still, there is optimism.

The lefthander said he is scheduled to throw another bullpen Saturday. If that goes well, he could be activated next week.

"It's slowly gotten better," Lee said. "The last two days have been drastically better than the four or five days before that."

Kyle Kendrick will take Lee's turn for the third time in Friday's series opener against Stephen Strasburg and the Washington Nationals.

"On every throw, I didn't feel anything," Lee said. "There are a couple of exercises I do where I can barely feel it. But compared to how it was before, it's safe to say it's on its way to being done."

Thome out

Jim Thome sat at his locker Tuesday not yet resigned to his fate. A month in the National League had already put considerable strain on Jim Thome's chronically cranky back.

"It's pretty much what I've had my whole career," he said.

In the past, Thome said, it could take three, five, or six days to improve. But Thome was placed on the 15-day disabled list Wednesday. The Phillies recalled catcher Erik Kratz to replace him.

A trip to the disabled list could benefit both team and player. Manager Charlie Manuel now has a full bench with the addition of the righthanded-hitting Kratz. And Thome reported to Clearwater, Fla., where he can see live pitching in extended spring training games.

But there are still lingering questions about the viability of this reunion, as heartwarming as it may be. Thome, who signed a $1.25 million deal during the winter, had 37 at-bats during a month of Grapefruit League play in March. That did not help his timing at the plate; he was just 2 for 18 with 10 strikeouts and no extra-base hits in the season's first month.

Manuel has said he wanted to play Thome "a couple of times a week, at least" at first base. That, also, is under consideration. Thome made four starts in the season's first 21 games. The manager insisted it can still happen.

"I think that we need to play him," Manuel said. "I think we're going to have to play him. When Ryan Howard comes back, more than likely every now and then he's definitely going to need a blow. He's coming off a serious injury and the fact he hasn't had any spring . . . to put him out there at first you're going to have to monitor him a little bit. And that would hopefully be Thome, if he's ready to hit."

Kratz was recalled because he was swinging a good bat, Manuel said, and was already on the 40-man roster. In 54 plate appearances, Kratz hit .294 with three home runs and four doubles for triple-A Lehigh Valley. He's played in 11 career major league games.

Extra bases

David Herndon has a right flexor pronator strain and will not throw for at least three weeks. The Phillies do not believe he is a candidate for surgery, assistant general manager Scott Proefrock said. . . . Domonic Brown strained his left hamstring Wednesday in a triple-A game. The team has termed his injury as "day-to-day."

Pitching prospect Jesse Biddle was removed from his Tuesday start after two batters because he was struck by a line drive on his left forearm. Proefrock said Biddle did not need X-rays and the decision to remove him was "precautionary."