CHICAGO—Rays reliever Chad Bradford stepped off the mound in the midst of his warm-up tosses after entering the game with two on and two out in the seventh inning and had to leave the game.

Bradford threw a few pitches to Dioner Navarro, then looked uncomfortable and stepped off the mound as Navarro motioned to the dugout for manager Joe Maddon and a trainer. After a brief discussion, Bradford left the field and Dan Wheeler came on to replace him.

Bradford opened this season on the disabled list after undergoing surgery Feb. 5 to remove loose bodies from his pitching elbow. He rejoined the Rays on June 27 and had made 10 appearances since then prior to tonight.

Updating: Bradford said he felt fine warming up in the bullpen but his back grabbed him “out of nowhere” on his fourth or fifth warmup ptich.

“I felt something grab, then I tried another one and it really got there where I can’t really even move a whole lot, so I thought I’d better shut ‘er down,” Bradford said. “I’ve kind of been through this before – when it starts to grab, if you push it, you can really hurt something.”

Bradford had lower back surgery in March 2005 and opened the season on the disabled list for the A’s. He didn’t begin a rehab assignment until late June.

Bradford said the Rays hadn’t slated him for an MRI or X-ray tomorrow just yet and he hoped the problem would clear up on its own overnight. 

“We’ll see what happens tomorrow and hopefully it’s just a bump in the road, maybe a little spasm,” he said. “We’ll know more tomorrow.”