TORONTO -- Red Sox right-hander Tim Wakefield threw a bullpen session before Tuesday's game at Toronto and is not yet healthy enough to return to Boston's starting rotation.
Wakefield, 11-3 with a 4.31 ERA, has been out since July 18 with a sore back that has led to nerve irritation in his left calf, forcing him to walk with a limp.
The 43-year-old knuckleballer made his first minor league rehab start on Saturday, allowing two runs and three hits in 3 1/3 innings with Triple-A Pawtucket.
Boston, which has won just four of 13 games and is still without right-hander Daisuke Matsuzaka, had hoped Wakefield would be able to rejoin the rotation later this week. But manager Terry Francona said there was a "pretty good chance" Wakefield would make another Triple-A rehab start Friday.
"This is a tough decision to make because we all think he can help us on the mound," Francona said. "But there's some other issues involved, like fielding your position, is he going to get weaker, is he going to hurt himself in another area. So we'll do the best we can.
"We all know what's wrong with him," Francona added. "At some point he's probably going to need a surgery. If he has the surgery this week, we're probably not going to have him available next week. We're trying to figure out what to do."
Boston did get infielder Kevin Youkilis back Tuesday. The infielder was eligible to play after serving a five-game suspension for charging the mound and throwing his helmet at Detroit right-hander Rick Porcello on Aug. 11. Also, outfielder J.D. Drew started for Boston after missing the past two games with a sore groin.
Catcher Jason Varitek was scratched because of muscle spasms in his neck.
The Red Sox were without second baseman Dustin Pedroia, who returned to Boston Tuesday afternoon, arriving at hospital shortly before his wife gave birth to the couple's first child, Dylan. Francona said he was not sure when Pedroia would rejoin the team.
"I told him his first responsibility is Kelly and that child," Francona said.
Also, pitching coach John Farrell left the team Tuesday and returned home to Cleveland to deal with a personal matter. Bullpen coach Gary Tuck replaced Farrell.