WASHINGTON -- The Nationals are planning to check the medical records of San Diego State right-hander Stephen Strasburg to make sure his back injury is not serious.

On Wednesday, Strasburg pitched 7 1/3 innings against New Mexico before leaving the game with a back cramp.

The Nationals have the No. 1 overall pick in the 2009 First-Year Player Draft, and they are expected to select Strasburg, who is 13-0 with a 1.24 ERA and 180 strikeouts this season.

"I'm not trying to hide anything or avoid the question: If the Draft were today, Strasburg would be the player, but he is a pitcher and things could change within a month," Nationals acting general manager Mike Rizzo said recently. "That's how I answer the question. He is the top guy on our Draft board."