Al Behrman, Associated Press
Houston Astros catcher J.R. Towles, right, talks with relief pitcher Brandon Lyon in the ninth inning of a baseball game against the Cincinnati Reds, Wednesday, May 4, 2011, in Cincinnati. Lyon gave up three runs in the inning and was the losing pitcher in the game won by Cincinnati 3-2.

CINCINNATI — The Astros have sent struggling closer Brandon Lyon back to Houston to have his right shoulder examined for weakness.

Lyon failed to retire any of the five batters he faced during a 3-2 loss to the Reds on Wednesday afternoon. He came into the game trying to finish off a one-hitter, but gave up a walk, four hits and three runs.

Lyon converted 20 of his 22 save chances last season, when he went 6-6 with a 3.12 earned run average. Already, he has blown four save chances in eight tries. The loss on Wednesday left him 3-2 with a 7.15 ERA. Lyon has given up 21 hits and nine runs in only 11 1-3 innings.