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03/04/10 1:05 PM EST

Berkman to make spring debut Friday

Slugger to open vs. Tigers as DH, to play field on Saturday

KISSIMMEE, Fla. -- Astros first baseman Lance Berkman is scheduled to make two at-bats as a designated hitter in his Grapefruit League debut on Friday against the Detroit Tigers in Lakeland, Fla. Houston manager Brad Mills said Berkman will start at first base on Saturday.

Berkman, who bruised his knee during baserunning drills on Sunday, missed Thursday's spring opener because of swelling in his knee. He's taking ground balls and batting practice, but he's been limited in the amount of running he can do.

"I want to play, but I just work here," Berkman said jokingly. "It's better. It's not quite as swollen. It's just a little puffy."

Berkman got an injection of shark cartilage into his left knee on Thursday. Shark cartilage is commonly used to treat arthritis.

Berkman, who is listed as day-to-day, was taken for an MRI on Monday after experiencing discomfort and swelling. Houston team medical director Dr. David Lintner reviewed the MRI results on Tuesday and confirmed the original diagnosis of Dr. David Crumbie.

Berkman had minor surgery on his left knee in 1999 and underwent surgery following the 2004 season on his right knee to repair a torn anterior cruciate ligament. He said his left knee gave him some discomfort at different points in the winter.

Brian McTaggart is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.