CHICAGO -- San Francisco Giants right-hander Mike Leake was placed on the 15-day disabled list because of a strained left hamstring.
Leake (9-6), acquired from Cincinnati last week for two prospects, was scheduled to make his second start for the Giants on Friday against the Cubs. He was scratched in favor of Ryan Vogelsong after his hamstring tightened during routine sprints Monday at Atlanta.
Leake threw before Friday's game to test his leg.
"We decided to go ahead and put him on the disabled list and give him the full 15 days to make sure he's fully recovered," Giants manager Bruce Bochy said. "It's not worth the risk to try to get him ready for the next start."
The Giants recalled left-hander Josh Osich from Triple-A Sacramento before Friday's game to take Leake's roster spot.
It's likely that Leake will miss two starts. But Bochy said he wants the right-hander, the Giants' lone trade deadline acquisition, fully healthy down the stretch.
Defending champion San Francisco is in a tight wild-card race and entered Friday's game three games behind first-place Los Angeles in the NL West.
Leake lost his first start with the Giants at Texas on Sunday. He allowed two runs, both on a homer by Josh Hamilton, in 6 1/3 innings.
"I'd rather have him for nine completely healthy starts than maybe one or two where he's not 100 percent," Bochy said. "Then you have the risk of going ahead and starting him with the hamstring still lingering there and losing him for the rest of the way.
"This is the wisest move. With the way he bounces off the mound and the way he plays the game, he uses his legs so much."