Rangers starter Kevin Millwood left Sunday's game against the Houston Astros in the fourth inning with a strained biceps tendon. Millwood, the Rangers' Opening Day starter, allowed six runs on nine hits and one walk in 3 1/3 innings. The right-hander left during the Astros' seven-run rally in the fourth that gave them a 9-4 lead. The injury is not considered serious, as it has nothing to do with the shoulder or the elbow. Millwood is expected to be re-evaluated on Monday.