Harden was tentatively scheduled to throw a bullpen session -- his first since Feb. 15 -- on Tuesday, but the injury-prone hurler developed soreness in his lat muscle while throwing long toss on Sunday. It's the same discomfort that sidelined Harden a month ago, though not of the same degree, Geren said.
The news came just two days after the A's skipper admitted Harden wouldn't be ready to join the rotation by Opening Day. He entered camp as a favorite to win the fifth-starter spot.
Harden has seemingly never had health on his side, as evidenced by a career that has been hampered by a rash of injuries. Since going 11-7 with a 3.99 ERA in 31 starts during the 2004 season, he has made at least 20 starts in just two of the six seasons that have followed, and has endured nine disabled-list stints -- six of them coming in Oakland -- throughout his career.