Garcia was lifted from the game after walking Kevin Plawecki on four pitches to start the inning. He threw 33 pitches and gave up a first-inning grand slam to J.D. Martinez.
It was unclear initially if Garcia was removed because of injury or performance.
The 24-year-old Garcia made 28 starts for the Astros this season, posting a 3.30 ERA and 167 strikeouts.
Right-hander Jake Odorizzi came into the game to replace Garcia.