MILWAUKEE -- Pirates manager John Russell is tinkering with his starting rotation.

Tom Gorzelanny will be recalled from Triple-A Indianapolis to start Saturday's game in place of Jeff Karstens, who will be pushed back two days to start the series opener against the Cubs.

The move allows Karstens to face the team he shut out over six innings in his National League debut on Aug. 1. It also keeps the right-hander fresh. Karstens started the 2007 season on the disabled list with New York and had a 60-day DL stint with a broken right leg in the middle of the season. This year, he has 28 innings in the Majors, as well as 68 2/3 innings in the Yankees' farm system before his trade to Pittsburgh.

"His workload this year has been a lot more than last year," Russell said. "We're monitoring him, giving him a couple extra days here and there. It's just to make sure he's strong and he feels good."

Karstens' start on Monday pushes Ian Snell to Tuesday and puts Jason Davis' status in the air. Paul Maholm will still start Sunday. Davis, like Karstens, has seen more action as a starter than he did last season, when he worked exclusively out of the bullpen.

"Our whole plan is the guys that have thrown more innings than they have last year, we're going to start monitoring that a little bit," Russell said. "It's not that we're going to shut them down or anything. But we'll get to a point with the extra starters that we can give guys extra days between their starts to plan it out that way. Have we got it set in stone yet? No."

With September approaching, another reinforcement is on the way. Right-hander Ross Ohlendorf, picked up with Karstens in the Xavier Nady trade, is 2-3 with a 3.74 ERA in five starts for Indianapolis.

"It's no secret when we've got Gorzelanny here now that at some point we'll probably want to get Ohlendorf up here," Russell said. "Now you have seven starters to finish out the year, so some guys are going to pitch more than others."