DETROIT -- Phil Coke's ill-fated step coming off the mound Monday night will cost him at least the next couple weeks. It will also push prospect Andy Oliver into the Tigers' rotation.

The team knew enough Tuesday morning to make a roster move, placing Coke on the 15-day disabled list with a bone bruise in his right foot. Detroit purchased the contract of lefty Adam Wilk from Triple-A Toledo to take Coke's place for now as an extra reliever, giving the Tigers an eight-man bullpen for the next four days until Coke's rotation spot comes back around on Saturday.

The Tigers took the mystery out of that spot quickly by announcing they'll recall Oliver from Toledo to make the start Saturday night against the Red Sox at Comerica Park. He's expected to then remain in the rotation to fill the spot the following weekend at Chicago against the White Sox.

Coke suffered the injury when he tried to chase down Ben Zobrist's bunt attempt in the fourth inning Monday night. Though the initial diagnosis was an ankle injury, a later exam revealed an extra bone in Coke's foot, the left-hander said after the game. It collided with another bone in his foot when he stepped awkwardly on the cutout between the mound and home plate.

Coke had no idea how long it would need to heal, guessing it would be day to day. A follow-up diagnosis clearly suggested longer than that, though the Tigers had no firm timetable for recovery.

"I was told last night that, in the opinion of the physicians, he would definitely not able to make his next start," manager Jim Leyland said.

Coke owns a 1-5 record and 3.81 ERA, but has a 2.89 ERA in five May outings along with a .238 opposing batting average. He's winless since April 14 through a combination of lack of run support and bullpen woes.

Wilk is 3-4 with a 3.86 ERA in eight starts at Toledo, but the Tigers have seen the 23-year-old as a relief prospect since he made a lasting impression in Spring Training. He'll give Detroit a third lefty reliever for the time being, joining lefty specialist Daniel Schlereth and long man Charlie Furbush, who threw 3 2/3 scoreless innings in Coke's place to earn his first Major League win on Monday.

"Wilk is here temporarily, most likely until Oliver pitches Saturday," Leyland said.

Oliver and Furbush had been viewed as the Tigers' best two starting prospects at Toledo, but with different styles. Oliver has a 4-3 record and a 3.26 ERA in eight starts for the Mud Hens, striking out 48 batters over 49 2/3 innings, while showing the ability to get quick outs and work deep into games.

"We decided at this time to leave Furbush in the bullpen and bring Oliver to pitch [Saturday]," Leyland said. "I'm not going to get into comparisons. That discussion was held by all the brainpower in the organization, including most of all the minor-league staff. And they felt right now Oliver would be the guy to pitch the game. And that's what I go by."

Oliver went 0-4 with a 7.36 ERA in five starts for the Tigers last June and July, filling a rotation spot after Rick Porcello was sent down to work through a sophomore slump. Oliver's strong performance led to speculation on when he might return to Detroit, but the success of Detroit's current starters ensured that his path was blocked.

"Oliver's obviously a top prospect," Leyland said. "Is he ready? I can't answer that. This is one of those deals where if Coke hadn't been injured, we wouldn't be talking about this right now, today. We might be at some point in the season, but we would not be talking about it today."

To make room for Wilk on the 40-man roster, Detroit designated right-handed reliever Robbie Weinhardt for assignment. The 25-year-old sinkerballer was up briefly with the big club in April, but has struggled at Toledo. The Tigers will wait to see if he clears waivers and can have his contract outrighted to the Mud Hens.

"I don't know if he lost his sinker as much as he just got it up too much," Leyland said. "High sinkers are not good."