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06/20/08 7:27 PM ET

Boone late scratch from lineup

Nats third baseman felt discomfort prior to batting practice

WASHINGTON -- Aaron Boone was a late scratch from the Nationals lineup Friday against Texas after feeling pain in his surgically repaired left knee. Boone, originally slated to play third base, said he felt discomfort getting ready for batting practice.

"It's not something I'm overly concerned about at this point," Boone said. "It kind of just made me go 'Whoa.'"

Boone played down any speculation that the pain was anything more than something temporary. Boone said this is the first time all season he's felt a pain he said is "bugging" him. He said he thinks playing on the turf in Minnesota might have aggravated something.

"It's just a little banged up from the last couple of days," Boone said. "You don't play on [turf] much anymore. I used to love playing on it."

Kory Casto was inserted into the lineup in place of Boone, who is hitting .266 with five home runs and 16 RBIs. Boone has played third and first for the Nationals so far this season.

Zachary Osterman is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.