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6/25/2013 10:08 P.M. ET

Maxwell dives for ball, suffers mild concussion

Right fielder's head hits ground, while left wrist rolls under his body

HOUSTON -- Astros outfielder Justin Maxwell, who was activated from the disabled list a week ago after missing nearly two months with a fractured bone in his left hand, was removed from Tuesday's game with a mild concussion after diving for a ball in the outfield.

Maxwell, who was starting in right field, made a diving attempt in the gap in right-center to catch a ball off the bat of Matt Carpenter, who wound up with a three-run triple to put St. Louis ahead, 6-0, in the fourth. Maxwell's head hit the ground hard and his left wrist rolled under his body, but it was immediately unclear why he left the game.

Maxwell, who was replaced by J.D. Martinez, entered the game hitting .237 with one homer and six RBIs and had gone 5-for-21 with a double and four walks since returning from the disabled list on June 18.

He had started all seven of Houston's games since his return. He was placed on the disabled list April 24 with a fractured left hand, suffered when he was hit by a pitch by Seattle's Hisashi Iwakuma. He missed 51 games.

Brian McTaggart is a reporter for MLB.com and writes an MLBlog, Tag's Lines. Follow @brianmctaggart on Twitter. This story was not subject to the approval of Major League Baseball or its clubs.