A herniated disk in the back of Boston right fielder J.D. Drew could leave a hole in the Red Sox’ offense.

AP / Elise Amendola

TORONTO — The Red Sox received an unpleasant surprise yesterday afternoon when they learned that outfielder J.D. Drew is suffering from a herniated disk in his back.

Drew has suffered from chronic back pain throughout his career and had a flare-up last Sunday at Fenway Park against Toronto. He missed the three games of a series in Baltimore earlier this week, but it was thought he’d be able to return to action last night here in the opener of a weekend set against the Blue Jays.

Red Sox manager Terry Francona had Drew in the lineup, but the right fielder was scratched after he woke up yesterday morning with some discomfort. As a result, he was sent to a local hospital for an MRI, where it was learned he had a herniated disk.

There’s no word on how long he’ll be sidelined.

“I’m hoping not,” he said of going on the DL “We’ve got to figure it out because I don’t want to miss any more time. It could be better [today], or it could be better on Sunday. That’s the way it’s kind of been all along. I thought I was heading in the right direction [Thursday] because I felt better. But now I’m stiff and we’re going to try to get it calmed down and get back to baseball activities without going on the DL.”

Drew said he felt good Thursday and thought he’d be able to play last night. Yesterday morning he was a little stiff and took a hot bath in an attempt to loosen the stiffness. After the bath, his back locked up, and Drew said he felt “progressively worse” during the day. He was having difficulty walking through the clubhouse.

“We’re going to try to treat it and get it calmed down,” he said. “It’s hard to say exactly what the right direction is right now, but we’ll keep treating it.”

The problem is similar to an injury he had earlier in his career with the Cardinals. While in St. Louis, Drew tore the sheath three-quarters around his spine in the area where he has the herniated disk. The Red Sox were expecting a medical report last evening.

“I tore that same sheath around my spine when I was in St. Louis,” he explained. “It’s similar and could be the herniated disk from the previous injury. We just need to get a better look at it.”

In 2001, Drew missed 12 games when he first suffered the injury. He said yesterday he remembers how sharp the pain was.

“I literally could barely walk at that time,” he said. “Eventually it healed up and got better. I’ve done it a couple of times this season, including [during the March trip to] Japan. But I didn’t seem to do it as bad last Sunday, and for whatever reason my back is really guarding against letting a spasm out. If I sit down and try to relax, when I stand up, I get stiff and I can hardly move.”

jmcdonal@projo.com