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03/23/12 4:37 PM ET

Stanton, Dobbs, LoMo aiming for Opening Day

JUPITER, Fla. -- They've resumed baseball activities, but will they be ready for Opening Day?

The next few days will be telling for Giancarlo Stanton, Logan Morrison and Greg Dobbs.

The three began jogging, fielding and hitting on Thursday, and they continued their respective programs on Friday. If all goes well, they will be used as designated hitters in Minor League games, perhaps as early as Saturday.

The Marlins' offense has been sluggish without these three key players in Spring Training.

Manager Ozzie Guillen says that the team needs some answers on their health, as the club is trying to finalize the Opening Day roster.

"We keep waiting," Guillen said. "I need to know exactly where we are, for our process. Are they available?

"They're going to DH in the next couple of games, then they're going to play in the Minor Leagues, and then up here. So we can see how much longer we're going to wait, or if we're going to put them up here in the lineup."

With the season set to open on April 4 against the Cardinals at Marlins Park, time is running short on getting them ready for regular-season action.

Stanton (left knee), Morrison (right knee) and Dobbs (left hamstring) were cleared to begin baseball activities after being examined by team physician Dr. Lee Kaplan on Tuesday in Miami.

"I fast-jogged a little bit yesterday," Stanton said. "I'll pick it up today. I got positive feedback, and we'll get this progress for Opening Day going."

Dobbs' hamstring responded favorably to some light jogging on Thursday.

"We'll ramp it up a little bit more," Dobbs said.

Morrison is a little more guarded. He is coming off the December surgery on his right knee, and he has dealt with some inflammation.

Asked if Opening Day is realistic, Morrison said, "That's the plan. That's what they're trying to get me ready for. If there are no setbacks, yeah."

Still, he isn't completely confident that he'll be in the lineup when the Marlins open their new ballpark.

"I don't think I'm going to tell them," Morrison said. "I think the knee is going to tell me. The knee is going to tell everyone. I can't tell it what to do."

Morrison is set to be a DH in a Minor League game on Saturday on a back field at the Roger Dean Stadium complex.

Stanton, meanwhile, could be a DH as early as Monday or Tuesday.

Dobbs isn't sure when he will see game action.

The Marlins have some decisions to make with the three, because the retroactive date to place players on the disabled list is Monday. If any player is used in Grapefruit League games after then, he won't be eligible to be put on the DL retroactive to that day.

For instance, if Stanton or Morrison play in Minor League games for the rest of the spring, and they aren't considered ready for Opening Day, they could be placed on the DL retroactive to March 26. Thus they would be eligible to be activated on April 10, when the team is in Cincinnati.

Under that scenario they would miss as few as the first five games of the regular season. Otherwise they could miss a few weeks.

Stanton is aiming to play in exhibitions with the big league club. At the latest he hopes to be in action for the April 1 game against the Yankees at Marlins Park.

"That's ideal, to play with the team at least a little bit," Stanton said. "You can't just go straight into Opening Day or whenever, without playing with them."

Stanton initially was sidelined after he was struck on the left wrist by a pitch on March 11. It was then revealed that he had been dealing with inflammation in his left knee. The knee actually bothered him a year ago, but he was able to play through.

Stanton has nine at-bats in Spring Training.

"If I'm going to be ready," Stanton said, "I'm going to have to be ready for at least a few games [with the regular club]."

Joe Frisaro is a reporter for MLB.com. He writes a blog, called The Fish Pond. Follow him on Twitter @JoeFrisaro. This story was not subject to the approval of Major League Baseball or its clubs.