FORT MYERS, Fla. -- Minnesota Twins left-hander Eric Milton will have another operation on his left knee.

	Milton

Milton, who had a torn meniscus repaired last August and missed a month of the regular season, has experienced recurring swelling after workouts this winter. He'll probably have the operation next week.

Milton's left knee is the one he uses to push off the mound.

"There's definitely some cartilage damage in there,'' manager Ron Gardenhire said Friday. "He thought he was getting better, but a couple days ago he felt some clicking in his knee.''

Johan Santana, who plugged holes in the rotation last year when Milton, Brad Radke and Joe Mays all spent extensive time on the disabled list, will replace Milton as Minnesota's starter on Saturday in Sarasota against the Cincinnati Reds.

"I think I've been through that situation before, so I think I'll be able to handle it,'' said Santana, who went 7-5 with a 3.24 ERA in 14 starts last season. "I'm sorry about him, you know? He's a great pitcher, he's one of the best here.''

The Twins are awaiting a complete diagnosis on Milton's knee, but it's likely he'll only need arthroscopic surgery.

Recovery from that procedure typically takes a month, but the Twins indicated a starting pitcher like Milton would probably need more than that to make up for the lost time in spring training.

"There's never a good time for this, but it's better for that to happen now as opposed to two months from now,'' general manager Terry Ryan said. "The good thing is it doesn't look anything more like a scope.''

Milton's return last September was a little shaky, but he turned in two fine starts in the playoffs. Aside from the swelling he insisted he was fine, and he didn't appear to have any problems until the latest setback this week.

"Milty's a warrior,'' catcher A.J. Pierzynski said. "He'd never say anything. I hit off him a couple times, and he looked great, I thought. You don't want to rush him -- maybe he rushed it a little bit last year and maybe that led to it.''

Milton had multiple tests on the knee that didn't show any damage this winter.

"He was looking fine, not altering anything he does,'' Gardenhire said. "The guy gets better every day, starts to feel better, and -- boom -- there you go.''

The Twins are relieved, though, to get this over with in the spring, especially with a capable replacement in Santana.

"We're going to get it straightened out,'' Gardenhire said.

Santana's promotion leaves a spot open in the bullpen for a long reliever, and veteran Jose Cabrera will compete with a handful of youngsters including Juan Rincon, Kevin Frederick, Grant Balfour and 2000 first-round draft pick Adam Johnson.