PHOENIX -- The A's will definitely not have A.J. Griffin in the rotation to start the season, and the expectation is that Jarrod Parker will receive similar news come Monday.

Griffin had an MRI Friday on his right elbow that revealed a flexor muscle strain. He's been told to rest for three weeks, at which point he'll be allowed to start strengthening his arm again.

The reality is that he'll probably have to go through the equivalent of spring training all over again, so the A's aren't likely to see him taking the ball at all before sometime in May.

"Sometimes in spring training, your arm kind of responds one day and you are good to go," Griffin said. "It seems like every spring I have a scare, and it usually works itself out. In this case, it's been really uncomfortable throwing. I can't get extension with my fastball.

"I want to get back to being the pitcher I am. I need to take it easy and get back to 100 percent."

Oakland manager Bob Melvin isn't turning handsprings at losing Griffin, but he acknowledges the MRI results could have been much worse.

"It was good news for us to learn that the MRI showed it wasn't a surgical issue," Melvin said. "Now we shut him down for three weeks, then he'll start strength work."

At the same time, the A's are miles away from being able to even project a timeline for Griffin's return.

The same could be true for Parker, who said Saturday morning that it was a dead guess on his part when he suggested he, too, might miss three weeks.

"I could be checked out Monday and be back throwing Tuesday, Wednesday or Thursday," Parker said.

The reality is that Parker is still feeling pain in his right forearm, the same place he had discomfort in September and October. He will meet in Florida Monday with Dr. James Andrews, the specialist who did his Tommy John-style ligament replacement surgery in 2009 that cost him the 2010 season.

"It's a little different than last year," he said of his current dilemma. "It's in a similar area, but it feels different."

Parker said he takes some comfort in that he'll be meeting with Andrews given the physicians' knowledge of Parker's arm, and he's hoping for the best. But the fact that the problem was getting worse the longer he got into spring training doesn't generate extremes of optimism.

Melvin said that while Jesse Chavez and Tommy Milone are the likeliest names to be promoted into the rotation competition with two vacancies now staring Oakland in the face, he wasn't willing to limit the pool of talent.

Arnold Leon, who started Saturday's split-squad game against the Rangers, is a pitcher Melvin has talked about glowingly this spring.

  • Craig Gentry, the outfielder who has yet to play in a spring game for the A's because of back problems, will take a step forward by participating in a half session of batting practice thrown by the coaching staff. Gentry is hopeful that he "could get into a game by the end of next week." It's likely the A's would put him in minor league games where he could build up at-bats by leading off every inning, but nothing is set yet.

  • Reliever Ryan Cook will test his shoulder with a session of live batting practice Sunday, meaning game action could be just a few days away.

  • Lefty Eric O'Flaherty, who is scheduled for a July return after last year's Tommy John surgery, is due to throw a bullpen session Saturday.

    For more on the A's, see John Hickey's Inside the A's blog at ibabuzz.com/athletics. Follow him on Twitter at twitter.com/JHickey3.