NEW YORK -- Red Sox lefty Felix Doubront, who has been in a rest period since Aug. 9, might not make his next start until the end of next week, according to manager Bobby Valentine.

If that ends up being the case, Doubront could go on the disabled list retroactively, meaning Boston could call up another pitcher until he returns.

Doubront is keeping active, however. Valentine said that Doubront was going to throw three simulated innings at about 45 pitches before Friday night's game against the Yankees.

"He had a nice active rest period where he's continued to throw on flat ground but nothing off the mound, so we have him a little up and down session in the bullpen today," said Valentine. "There will be another one of those planned where he'll do it longer and then he'll be able to pitch in a game and throw his 100 pitches or so."

Aside from the normal arm fatigue Doubront has felt as he approaches a career professional high in innings pitched, Valentine also said that there's been a knee issue that perhaps led to his rest period.

"So, you know, he had a little knee situation that we wanted to make sure cleared up," Valentine said. "He'll be ready this next week to pitch. If we decide we don't need him until at the end of the week, we might even take that amount of time."

Papi takes batting practice, itching to return

NEW YORK -- After days of snail-like progress, there was finally some good news regarding David Ortiz on Friday.

Ortiz, who had been in the midst of a five- or six-day rest period, was totally free of pain in his right Achilles on Thursday. He took indoor batting practice before Friday's game.

"I just did soft toss," Ortiz said. "The thing is, after I hit, it doesn't matter if it's soft toss or on the field, because all the twisting, I was getting really sore. So they shut me down for a while, because I've been feeling good and I've been improving. They want me to do soft toss only today.

"If tomorrow I'm good, I feel like I feel right now, then I will hit on the field. And if the next day I feel like I keep on improving and feeling better, we have some other activities and go from there."

The key for Ortiz is that his injury is finally trending in a positive direction.

"I've been feeling better," Ortiz said, "because I think that spot, it was very tender. ... [Running] was meant to help, but I don't think it was helping, because it was getting too sensitive. They shut that down, we'll keep on doing some other stuff, but we're not as aggressive as we were. I've been feeling better though."

The Red Sox are 12-17 without their star slugger. Despite the improvement in Ortiz's status, he's all but certain to miss this weekend's three-game series against the Yankees.

That one big hot streak has eluded the Red Sox of late, and Ortiz isn't being brash when he suggests that his absence could be a big reason why.

"When you come to be part of this organization, you came to earn a position, because of the history of the things that you do and I know I'm a force in this organization," Ortiz said. "I know I'm a run producer. That's what I was doing this year until I got hurt, and, you know, we have had a lot of games that we have had lack of producing.

"Yeah why not? That'd probably be the factor of a game not being able to score runs or might be some other factor involving it, but like I say, I know I'm a force here. What would you like to have more than me as a player when it comes down to producing runs to win ballgames?"

It has been a killer for Ortiz to miss two straight series in the Bronx, a place he loves to perform and has thrives over the years.

"You have no idea, man. It's frustrating," Ortiz said. "It's just something that -- I like actions. I like helping this ballclub as much as I can, and not being able to play and seeing that the ballclub needs me, it's just hard to deal with."

Ortiz appreciates how the medical staff has handled his treatment.

"We have doctors, they know what they're doing and they know how to deal with injuries," Ortiz said. "As much as I want to be out on the field, at the same time, they know that there's a career behind the whole thing and they don't want to face a situation that just because of rushing things they get to ruin the whole thing."

Needing roster spot, PawSox release Prior

NEW YORK -- If right-hander Mark Prior does return to the Major Leagues for the first time since 2006, it appears it won't be with the Red Sox.

Prior had been pitching for Triple-A Pawtucket since May, but he was released on Friday.

The PawSox needed to clear a roster spot for Pedro Beato, the player to be named from the Mets in the Kelly Shoppach trade.

In 19 games with Pawtucket, Prior was 1-0 with a 3.96 ERA. Over 25 innings, he had 38 strikeouts while holding opponents to a .172 average. However, he had 23 walks.