The team announced that it was a viral upper respiratory infection -- and not his troublesome right ankle -- that caused Peavy to leave his start at PETCO Park.
Peavy, who threw 33 pitches in the first inning, left for the clubhouse after getting out of the inning.
Josh Geer, who turned 26 on Tuesday, entered the game in the top of the second.
The one-inning outing marked the shortest stint of Peavy's career. His previous shortest start came on Aug. 25, 2003, in Arizona, when he pitched two innings.
Peavy, who had won his previous three starts, rolled his ankle while running the bases in a May 22 start against the Cubs. In his last start, on May 27 in Arizona, he allowed eight hits and four runs before leaving after 6 1/3 innings.
It was in the start against the Cubs where Peavy rolled his right ankle, an injury that gave him fits in his last start against the D-backs.
As recently as Friday, Peavy, who is 5-5 with a 3.67 ERA this season, was hobbling on his ankle. Peavy spent several days working with the training staff and even went as far to wear a protective boot to bed to hold his foot in a neutral position so that his ankle would heal properly.
Corey Brock is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.