Athletics designated hitter Frank Thomas was placed on the 15-day disabled list Saturday because of a strained right quadriceps.

Thomas was in uniform and scheduled to bat fourth against the Minnesota Twins before the team made the surprise announcement less than two hours before the start of the game. The clubhouse was closed when the move was made and neither Thomas nor Oakland manager Bob Geren could be reached for comment.

This is the second time Thomas has been on the DL this season. The 40-year-old slugger, who is tied with Willie McCovey and Ted Williams for 17th place with 521 career home runs, missed 55 games with tendinitis in his right quad from May 28-July 30.

Thomas had complained about soreness in his leg in recent days and acknowledged he had trouble pushing off with his right foot. He was mired in a career-long 0-for-23 slump before going 8-for-21 (.381) over his last six games.

Thomas began the season with Toronto but batted only .167 with three home runs and 11 RBIs for the Blue Jays. He was released on April 20 and signed with the A's four days later. In 55 games with Oakland, Thomas hit .263 with five home runs and 19 RBIs.

The A's also reinstated right-handed reliever Keith Foulke from the disabled list, called up outfielder Aaron Cunningham from Triple-A Sacramento, optioned right-hander Dan Meyer to Double-A Midland and transferred right-hander Andrew Brown to the 60-day DL.

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