Oswalt leaves with back strain

CHICAGO -- Houston Astros right-hander Roy Oswalt left Tuesday night's game against the Chicago Cubs in the second inning because of a left lower back strain.

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.