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Collin Cowgill, left, has been demoted to Las Vegas to make room for Andrew Brown.

ATLANTA -- Collin Cowgill, who had a solid spring training and a grand slam on Opening Day, has been demoted to Triple-A Las Vegas to clear the roster spot for the promotion of fellow outfielder Andrew Brown.

Cowgill, 26, has hit .157 (8-for-51) with two homers and eight RBIs with the Mets. All 10 of his starts came in center field. He had been hitless in his final 13 at-bats and also had a costly misplay Monday in Miami, when he broke backward on a ball that dropped in front of him and contributed to Bobby Parnell's blown save.

Cowgill was the first player in franchise history to hit a grand slam in his Mets debut.

He was acquired from the Oakland Athletics on Dec. 18 for minor league corner infielder Jefry Marte. Marte, 21, is hitting .267 with no homers and eight RBIs in 86 at-bats with Double-A Midland this season.

Brown, 28, has hit .367 (36-for-98) with two homers and 27 RBIs in 25 games with the Las Vegas 51s. Brown had an active 11-game hitting streak and a Pacific Coast League-leading 13 doubles.