An MRI revealed no damage in the shoulder of Nationals' star rookie pitcher Stephen Strasburg. Washington will monitor him closely and see how he responds. It's uncertain how long he'll be out.

Strasburg, the Nats rookie phenom who has electrified baseball since making his major league debut on June 8, was scratched from what would have been the 10th start of his career on Monday night just minutes before he was to take the mound against against the Braves in D.C. He said he had trouble getting loose in the bullpen while warming up and the Nats chose to start Miguel Batista instead.

Strasburg, who turned 22 last week, has gone 5-2 with a 2.32 ERA and 75 strikeouts against just 15 walks in 54 1/3 innings pitched. The Nationals, who selected Strasburg with the No. 1 overall pick in the 2009 draft, have been carefully watching his workload this season.

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