MILWAUKEE -- Zack Greinke took a big step toward returning to the Brewers' rotation on Thursday by throwing off a bullpen mound at Miller Park. It was his first mound work since he was shut down in mid-March to let a cracked left rib heal.

Greinke still faces weeks of rehabilitation. He will have to throw a series of bullpen sessions and perhaps simulated games before he's cleared for a Minor League rehab assignment. That process could take 10 days to two weeks. Then he will have to build his pitch count in Minor League games over the course of another three or four weeks.

"He's been really throwing the ball well," said manager Ron Roenicke, adding that the Brewers will be cautious. "Once his arm is built up and strong, then you can push him."

Following are some updates on the four other Brewers on the 15-day disabled list:

• Catcher Jonathan Lucroy was to begin a rehab assignment with Double-A Huntsville on Thursday night. Defensively, he's ready to return to the Majors after missing all of Spring Training with a fractured right pinkie finger, it's merely a matter of him getting comfortable at the plate.

"He's wanting to get that right, and we are, too, before he comes back here," Roenicke said. "Everybody is different, but it can be as low as five at-bats for some guys, and then as many as 30 for somebody else. It was 30 or more for me."

Lucroy has been texting updates to bench coach Jerry Narron, and the team will receive daily reports from Huntsville manager Mike Guerrero.

• Reliever LaTroy Hawkins (shoulder) is slated to pitch on Friday for Class A Brevard County, and Manny Parra (back) on Saturday for Class A Wisconsin.

• Right fielder Corey Hart (strained rib cage), who will try hitting again on Friday, told 620-AM's Trenni Kusnierek that he'll see if acupuncture helps speed his return.

Brewers don't expect DL stint for Saito

MILWAUKEE -- Veteran reliever Takashi Saito remained unavailable to pitch on Thursday because of a sore left hamstring, but it does not appear that the right-hander will need to spend time on the disabled list.

"I would be very surprised if that happened," manager Ron Roenicke said. "We're just hoping it's a couple of days."

Saito had a similar issue in Spring Training, which delayed his unofficial Brewers debut, as well as during last season with Atlanta, when hamstring soreness preceded a shoulder injury that kept him off the Braves' postseason roster.

Saito was hurt facing his final batter of a forgettable home opener in which he surrendered two home runs and took the loss. He plans to be very careful this time.

"I'm not too sure [how long I will be sidelined]," Saito said through his translator. "I'm only playing catch. I haven't thrown off the mound yet."

Saito's thoughts on Thursday morning were once again back in Japan, where another large earthquake struck near his hometown, Sendai. He was still trying to gather information on the well being of his family members, including his parents, as the Brewers prepared to play their series finale with the Braves.

Estrada could join Brewers' regular rotation

MILWAUKEE -- Right-hander Marco Estrada will remain with the Brewers after his effective start on Wednesday, and he could pitch again earlier than April 16, the next date the club originally expected to next need a fifth starter.

"We're trying to still figure that out," manager Ron Roenicke said. "It's a possibility that he could end up being in the rotation to try to push back some of the other starters so they're not always on their fifth day. Sometimes they may be on their sixth. We're looking at it."

Estrada allowed four runs in six innings during his season debut on Wednesday and would have had a real gem had he not surrendered a three-run homer to the Braves' Jason Heyward in the sixth inning. It marked the first time the team needed a fifth starter to fill the void left by Zack Greinke's rib injury, and going forward, because of an off-day Monday, the club could get by with its four other starting pitchers until April 16, at Washington.

If the club opts to slot Estrada into a regular five-man rotation, he could start on April 12 at Pittsburgh instead. The decision will be based on a number of factors, including the outcome of Shaun Marcum's start on Thursday and the upcoming availability of reliever Takashi Saito, who was still out Thursday because of a sore left hamstring.

Last call

Nyjer Morgan, off to a nice start for the Brewers, started in right field on Thursday alongside center fielder Carlos Gomez. But manager Ron Roenicke didn't bump Gomez from the two-hole in the starting lineup. "It's way too early to make decisions on where guys are going to be," Roenicke said. "I watched Gomez hit all spring, and he was really consistent in what he was doing. I know he got out of that a little bit for a couple of games. We'll see what happens. I'm not saying we're going to stay with Gomez the whole year [hitting] second, but as long as I like what he's doing and Dale [Sveum, the hitting coach] likes what he's doing, I think that's a good spot for him." ... Left-hander Dan Merklinger has cleared waivers and been assigned outright to Double-A Huntsville. The team designated Merklinger for assignment on Wednesday to clear a spot for right-hander Marco Estrada on the 40-man roster.