Oswalt pitched a scoreless first inning then struck out the first two batters he faced in the second. After throwing a 1-1 pitch to Alfonso Soriano, catcher Ivan Rodriguez noticed something was wrong with Oswalt and met with him on the mound. He then waved for Astros manager Cecil Cooper and a team trainer.
Moments later, Cooper called left-handed reliever Wesley Wright to replace Oswalt. He left the game with Astros leading 1-0.
Oswalt entered 6-4 with a 3.66 ERA. He won his three previous decisions and was 4-1 with a 2.40 ERA in his last eight starts.