JUPITER, Fla. -- Outfielder Kirk Nieuwenhuis left Sunday's game with a bruised left knee, potentially complicating the Mets' already unstable outfield situation.

Nieuwenhuis suffered what he believes to be "a bad bruise" while sliding into second base in the seventh inning of Sunday's 6-4 loss to the Marlins. He stood up and tried to lead off second base on the next pitch, but his knee "just kind of buckled a little bit."

Because the visiting clubhouse at Roger Dean Stadium is located near the left-field foul pole, as opposed to behind the dugout, Nieuwenhuis accepted a ride off the field in a cart. He said he could have limped to the clubhouse, "but it would have taken me a while."

Nieuwenhuis, who is slated to open this season in a center-field platoon with Collin Cowgill, was scheduled to undergo testing later Sunday.

"Hopefully it's just a bad bruise," he said. "When I went to go take my lead it just kind of buckled a little bit, but I think the ligaments are OK."

If Nieuwenhuis misses any significant time, the chorus clamoring for outfield prospect Matt den Dekker to make the team may grow louder. One of the best defensive center fielders in the Minor Leagues, den Dekker became a fringe candidate for the Opening Day outfield last year when injuries struck Andres Torres and Jason Bay.

He is a year older and a more refined player this year, but den Dekker still draws criticism for the significant amount of swing and miss in his offensive game. The Florida native hit 17 homers over two levels of the Minors last season, but also struck out in more than a quarter of his plate appearances. Still, as a left-handed hitter, he could fit into a center-field platoon with Cowgill.

Gee hurls three frames in first outing since July

JUPITER, Fla. -- An admittedly "rusty" Dillon Gee climbed aboard the Roger Dean Stadium mound on Sunday and began firing fastball after fastball high in the zone. He was amped; for the first time since July, Gee was facing Major League hitters in a game.

"It's exciting just to be back out there again," he said after scattering three hits and a walk over three scoreless innings for the Mets against the Marlins.

Gee had not appeared in a Major League game since July 7, when he held the Cubs to one run over eight innings at Citi Field. After that game he began feeling numbness in his right hand, the early signs of a blood clot in his shoulder that required emergency surgery. Though Gee began throwing again before the end of the season, he did not return to game action.

That makes this an important spring for Gee, who is now fully healthy and slated to rejoin the back of the rotation. The injury, he said, is the furthest thing from his mind.

"I try to just put that behind me," Gee said. "I can't go out there and pitch timid. I felt great all offseason, so in my mind there's nothing to be worried about right now -- just getting better, that's it."

Mets bullpen coach departs for Classic

JUPITER, Fla. -- David Wright is not the only Mets employee headed to the World Baseball Classic.

Bullpen coach Ricky Bones departed the team Sunday to serve as pitching coach for Team Puerto Rico in the Classic. Bones, a Puerto Rican native, began working as New York's bullpen coach last season. Prior to that he was a pitching coach for six years in the Mets' Minor League system.

Bones compiled a 63-82 career record with a 4.85 ERA over 11 seasons as a pitcher for the Padres, Brewers, Yankees, Reds, Royals, Orioles and Marlins.

Minor League catcher Francisco Pena also left camp to join the Dominican Republic team. Wright departed Saturday to join Team USA.

Worth noting

• The Mets signed 29 pre-arbitration players to one-year contracts, the team announced Sunday. Among them were top prospects Travis d'Arnaud, Zack Wheeler and Matt Harvey.

• Mets vice president of public relations Jay Horwitz, who has gained fame this spring for his Twitter account @Jay_HorwitzPR, is wearing a David Wright wristband to commemorate the third baseman's departure for the World Baseball Classic. Horwitz said he will wear the wristband until Wright returns.