They spent the entire baseball season vying to be contenders in September only to discover their postseason hopes may rest more on medical reports than scouting reports.

"So much is going to depend on health," says Chicago White Sox general manager Kenny Williams, whose team is trying to stave off the Minnesota Twins in the American League Central. "This time of year, you've got to have healthy players to win.

"And if you don't, no one's going to feel sorry for you."

Virtually every contender is dealing with injuries. The White Sox just got back third baseman Joe Crede and have been without setup man Scott Linebrink (shoulder tendinitis) since July22. The Boston Red Sox acquired outfielder Mark Kotsay on Wednesday from the Atlanta Braves to replace injured outfielder J.D. Drew (strained back). They will be without third baseman Mike Lowell (strained side) until perhaps mid-September, but ace Josh Beckett (elbow inflammation) is scheduled to make his first start Friday in nearly two weeks.

The Tampa Bay Rays, leading the AL East, anticipate third baseman Evan Longoria (fractured wrist) and closer Troy Percival (knee) returning on Labor Day weekend. New York Yankees pitcher Joba Chamberlain (rotator-cuff tendinitis) is scheduled to throw a bullpen session today.

Arizona Diamondbacks outfielder Justin Upton (strained side) is scheduled to return this weekend for the first time since July. And injured Los Angeles Dodgers closer Takashi Saito (torn elbow ligament) is scheduled to throw off a mound this weekend.