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3/21/2013 9:45 P.M. ET

Braves mulling over spots to fill in their bullpen

LAKE BUENA VISTA, Fla. -- The Braves have the potential to possess Major League Baseball's best group of relievers. But with Opening Day less than two weeks away, it is still not clear exactly who will be in Atlanta's bullpen at the start of the season.

As of Thursday night, closer Craig Kimbrel, Eric O'Flaherty, Luis Avilan and Cory Gearrin appeared to be the only locks to begin the season in the Braves' bullpen. The two key omissions from this list are Jonny Venters, who has not appeared in a game since March 13, and Jordan Walden, who missed nearly a month of the Grapefruit League season because of a bulging disc in his back.

Despite Venters' long layoff, manager Fredi Gonzalez has continued to say the left-handed reliever is simply getting some extra rest during this year's extended spring season. Venters battled upper arm discomfort early last year and was placed on the disabled list in July with a left elbow impingement.

Venters completed a bullpen session on Thursday. The Braves will rest him on Friday before determining when he might again pitch in a game.

"We're just giving him a little breather right now," Gonzalez said. "I think he'll be fine."

Gonzalez also remains confident that Walden will have enough time to make his necessary preparations before Opening Day. Walden's one-inning appearance during Wednesday's game against the Pirates was his first since Feb. 23.

Pitching coach Roger McDowell has mapped out a plan for Walden to make four more appearances before the start of the regular season. Gonzalez said this might be sufficient for the right-handed reliever, who was acquired from the Angels in November in exchange for Tommy Hanson.

If Venters and Walden are both ready for the start of the regular season, the final bullpen spot will go to either Cristhian Martinez or Anthony Varvaro, who are both out of options.

Martinez's experience in the long relief role he has handled for Atlanta the past two seasons seemingly makes him the favorite for the spot. But he has allowed at least three runs in three of his seven appearances, including one against the Tigers' Double-A affiliate this week.

J. Upton hitting tape-measure jobs at Champion

LAKE BUENA VISTA, Fla. -- One month into his first spring season with the Braves, Justin Upton has already hit two of the longest home runs in Champion Stadium history, and has caused some longtime members of the organization to conjure memories of the long homers Andres Galarraga once hit at this venue.

Upton's latest monstrous shot came against Dan Haren in the sixth inning of Thursday night's 4-3 win over the Nationals. The blast soared over the top of the clock positioned at the top of the park's 60-foot scoreboard in left-center field.

"That ball was carrying, carrying and carrying," Braves manager Fredi Gonzalez said. "Wow. I don't know how far beyond the scoreboard it landed. That ball was hit pretty good."

After seemingly traveling at least 460 feet, Upton's ball hit off the roof of the batting cages located beyond the outfield wall and bounced to an unknown location. Bullpen coach Eddie Perez, who played with Galarraga in Atlanta, was unsuccessful in his search for the ball.

"There were some people back there waiting for autographs and I said, 'Where did it go?'" Perez said. "They said we saw it land, but then it disappeared in the grass or something."

Upton said he did not know whether this blast was longer than the one he hit over the top of Champion Stadium's left-field berm against the Marlins on Feb. 25. Former manager Bobby Cox and Perez both said they had not seen another player hit a ball over the berm since Galarraga, who played for the Braves from 1998 to 2000.

Francisco, Johnson looking to platoon at third

LAKE BUENA VISTA, Fla. -- Braves manager Fredi Gonzalez entered Spring Training hoping that Juan Francisco or Chris Johnson would begin the regular season as the club's starting third baseman. But with a little more than a week left in the Grapefruit League season, Gonzalez is planning to platoon the two players at third base.

"I think both of those guys are playing such great baseball," Gonzalez said. "Right now, I think it would be unfair to choose one as a starter."

Francisco is hitting .352 (19-for-54) with five home runs and a .667 slugging percentage. Concerns about him handling an everyday role center around his ability to hit left-handed pitchers and the offspeed pitches he'll see more consistently during the regular season.

Johnson is hitting .368 (21-for-57) with three home runs and a .561 slugging percentage. Along with sharing the third-base duties, the right-handed infielder could occasionally give first baseman Freddie Freeman a chance to rest.

Worth noting

• B.J. Upton has been making an hour-long commute from his Tampa-area home since the start of Spring Training. He will have a chance to play a couple of personal "home games" when the Braves travel to Clearwater, Fla, to play the Phillies on Friday and then send a split squad to play the Blue Jays at Dunedin on Saturday. Both Clearwater and Dunedin are located approximately 20 minutes from his home.

• Luis Avilan's command was not as sharp as usual on Thursday, as he allowed three runs and four hits in the seventh inning against the Nationals. It was the first time for Avilan pitching on back-to-back days this year. He completed one inning in a Minor League game on Wednesday.

Mark Bowman is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.