JUPITER, Fla. -- Rosters officially have to be set by Sunday, but Marlins manager Fredi Gonzalez plans on having his team in place well before that.

Gonzalez is hopeful to announce the 25-man roster that will open the season on Wednesday.

"I think it's important for the team to know who their teammates are," Gonzalez said Monday. "It's important for them to come together."

One unanswered question was resolved on Monday, when the Marlins acquired closer Jorge Julio and cash from the Diamondbacks for Yusmeiro Petit.

With the closer issue resolved, the spotlight turns to center field.

The center-field battle is down to three candidates, with the other two not likely to make the club.

Non-roster invitee Alex Sanchez is believed to be have the inside edge based on his previous Major League experience. But Eric Reed has had a solid spring, and he remains in the mix, as does prospect Alejandro De Aza.

Reed has one more option, so if he doesn't win the job, he can be sent to Triple-A for more grooming.

De Aza is the intriguing third choice. The 22-year-old who projected to begin in Double-A has been the surprise of camp. According to a number of scouts who have observed the Marlins all spring, De Aza clearly has the most upside and talent.

The initial plan had been not to rush De Aza, who shows he may end up being the long-term answer in center. So the team had been thinking of having De Aza open in Double-A for more seasoning. Then, if he is performing in a few months, the club could promote him.

Because of De Aza's progression, the club is less inclined to explore center field trade options.

Gonzalez said he is leaning toward a platoon situation in right field until Jeremy Hermida is ready.

Hermida is out with a bone bruise on his right kneecap.

Joe Borchard, a switch-hitter who is more effective against right-handed pitching, is viewed as the front-runner while facing righties. Either Cody Ross or John Gall could get the nod against lefties.

As of now, the Marlins are not viewing backup infielder Alfredo Amezaga as an outfield option. Amezaga isn't expected to play any outfield for the remainder of Spring Training. The switch-hitter saw considerable time in center field a year ago.