PHOENIX -- The Brewers' hopes that closer Trevor Hoffman will recover from a rib-cage injury in time for Opening Day are fading quickly.

"It's looking dim," manager Ken Macha said.

Macha made that pronouncement after head athletic trainer Roger Caplinger told him that Hoffman won't be back on a mound for another week or so. Because he would probably need to work a few side sessions before getting into a game, it's increasingly likely that Hoffman will be sidelined, and perhaps on the disabled list, when the Brewers play their regular-season opener on April 7 in San Francisco.

Hoffman has not pitched in a Spring Training game since March 13. In the days thereafter he developed a strain to the oblique muscle along his right rib cage, a new ailment for the 41-year-old pitcher, who is Major League Baseball's all-time leader with 554 saves.

He played catch Thursday and Friday but his improvement has since "plateaued," to borrow assistant general manager Gord Ash's description. Hoffman was shut down from throwing for a second straight day Sunday and received extensive treatment in the training room.

According to Macha, Hoffman might undergo an MRI scan to further investigate the source of his pain.

"I've never had one of these [oblique injuries], but I've been around enough guys over the years who have to know they can be temperamental and take a lot longer than anyone wants," Hoffman said. "There's nothing you can do. You just have to wait it out."

That's precisely what fellow free-agent pickup Braden Looper had to do. Looper suffered a similar rib-cage injury on Feb. 28 and did not pitch in a game until last Monday. He has worked two Minor League games and will finally be slotted into an "A" game Thursday.

Hoffman's situation is a bit different because he will not have to build up a pitch count like Looper did. Hoffman was not sure by which date he would have to be back on the mound in order to be ready for April 7.

"No idea," Hoffman said. "That's probably something Roger has thought over and discussed with [Macha] and Doug. I don't know what that drop-dead last day will be.

"But it's a big benefit for me that I don't have to 'build up' like a starter does. I feel like I was throwing the ball pretty good this spring in a matter of three outings. So I know what the parameters are going to be; it's just a matter of when I can go out and do it."

He was asked whether the injury had simply plateaued or had actually gotten worse. The answer was a bit murky.

"The whole thing is, until you get to where your end result is, it doesn't matter where you're at in the middle," Hoffman said. "You still have to get from Point A to Point B.

"So it's a daily thing. You come in and look at them [the trainers] and they look at you, waiting, and you tell them how things are. It kind of stinks."

The Brewers' top candidates to fill in for an injured Hoffman would be Carlos Villanueva, who has struggled this spring and was scheduled for three innings against the Giants on Sunday, or Seth McClung, who is currently stretched out as a starter in case Looper has a setback. McClung has six Major League saves; Villanueva has two.

Meanwhile Hoffman, a workout warrior, is doing his best to stay in good shape even while he cannot throw. That should also help speed his return once the oblique strain subsides.

"You don't want to let everything go," Hoffman said. "The body needs rest, but you can't neglect other things. You have to constantly maintain the other areas."