Mike Leake to miss Friday start, replaced by Ryan Vogelsong

CHICAGO -- Mike Leake will miss a turn in the rotation for the San Francisco Giants because of a strained left hamstring.

Acquired from Cincinnati last week, Leake was scheduled to make his second start for the Giants on Friday. Instead, Ryan Vogelsong will pitch against the Chicago Cubs.

Manager Bruce Bochy says Leake felt the strain in a pregame conditioning session during the recent series at Atlanta. An MRI showed no major structural damage. Bochy said he is unsure if the injury will force Leake to miss more than the one start.

Leake is 9-6 with a 3.52 ERA this season.