- Dempster had been scheduled to pitch Tuesday night against Atlanta and said he hoped he would only miss three starts, including one after the All-Star break.
But manager Lou Piniella said that was an optimistic view and that after talking with trainer Mark O'Neal, Dempster could miss up to three weeks and maybe a month.
The Cubs recalled right-hander Kevin Hart from Triple-A Iowa, one day after he'd been optioned back to the minors, and plan to put him in the rotation. He'll start Wednesday against the Braves.
Carlos Zambrano, on three days rest, made the start Tuesday night in Dempster's place.
"We were healthy for a day," Piniella said. On Monday, the Cubs had activated Aramis Ramirez, Reed Johnson and Angel Guzman off the disabled list. And now they've put one of their most reliable pitchers right back on.
"Dempster is sick about this and so am I," Pinella said. "It's something you never expect to happen. Just a freak thing."
Dempster is 5-5 with a 4.09 ERA in 17 starts for the Cubs this season. He made the switch back to starter last season after being the Cubs' closer for three years. He went 17-6 with a 2.96 ERA in 33 starts and was picked for the All-Star team in 2008.
One might wonder why the Cubs don't turn Dempster's rotation slot over to Sean Marshall. Well, Marshall's got 58 starts in the majors and he's 16-25 with a 4.81 ERA. Also, he's currently the Cubs' only lefty reliever and managers do like their lefty relievers.
Meanwhile, it's time for Hart to get his shot. He's 26, and in various stints with the Cubs he's pitched only 44 innings, all of them as a reliever. In the minors, though, he's often been a starter, and apparently a pretty good one. Career-wise, he's got a 4.09 ERA as a starter, with eight strikeouts (and 3.3 walks) per nine innings. In the majors, he's throwing plenty hard, averaging nearly 93 miles an hour with his fastball (though he's not likely to throw as hard when starting).
Hart's 26, and there's probably a good reason or two for the Cubs never having tried him as a starter with the big club before. Let's find out, though. I suspect that Hart isn't as good as Dempster, but maybe a tick or two better than Marshall. At worst, he's a luxury for the Cubs, as most teams don't have an option like Hart when a rotation mainstay does some fool thing and breaks a big toe.