JUPITER, Fla. -- Justin Ruggiano, a front-runner for the center-field job, hopes to perform baseball activities in a week.

The 30-year-old tweaked his lower back while fielding a ground ball in the outfield last Thursday, and an MRI showed a strain.

"The improvement I've had in the past five days is amazing," Ruggiano said on Tuesday.

Ruggiano was a bright spot for the Marlins in 2012, when he hit .313 with 13 homers and 36 RBIs in 91 games after being acquired from the Astros. He missed the final two weeks of the season because of a shoulder injury.

"Backs are very delicate, so we've got to make sure we take our time with him and make sure he feels good and comfortable before he progresses to anything on the field or throwing or anything like that," manager Mike Redmond said. "He'll just continue to get his treatments and see how it progresses."

Mahoney vying for Opening Day roster spot

JUPITER, Fla. -- Blocked by Orioles infielders Chris Davis and Mark Reynolds last season in Baltimore, first baseman Joe Mahoney just wanted a chance in the big leagues heading into 2013.

"Everybody had a really good year in Baltimore, so it was a tough spot," said Mahoney, who was selected off waivers by the Marlins on Nov. 30. "There wasn't much opportunity for me there, and they did me a solid [thing] by letting me go and test the waters a little bit."

The 26-year-old hopes to earn a spot on Miami's Opening Day roster with Logan Morrison recovering from right knee surgery and not scheduled to return until mid-April.

Mahoney, a sixth-round pick in the 2007 First-Year Player Draft out of the University of Richmond, was the Baltimore organization's Minor League Player of the Year in 2010 with the Class A Frederick Keys and Double-A Bowie Baysox. He batted .307 with 18 home runs and 78 RBIs, to go with 13 stolen bases.

The 6-foot-6, 240-pounder was called up by the Orioles before the All-Star break and made his Major League debut on July 7, 2012, in a start against the Angels -- going 0-for-3. Mahoney also had a pinch-hit at-bat against the Tigers in August for the injured Wilson Betemit. When Baltimore reached the postseason for the first time since 1997, Mahoney traveled to Florida and stayed in shape just in case Reynolds or Davis sustained injuries.

Four months later, on a young Marlins team with players fighting for roster spots, Mahoney went 2-for-3 in the cleanup spot against the Braves on Monday, hitting behind Giancarlo Stanton. Mahoney is 3-for-6 with an RBI and a run scored in two Grapefruit League games.

"This is my third Spring Training, and in Baltimore I was used to guys having that spot," Mahoney said. "Here it's fun because everybody is fighting for a spot, and [that] gives everybody that little extra lift to get out there and push each other. It's exciting to come over here and getting a new opportunity and a fresh start. I'm fortunate to have six years in my career to just establish myself, work hard and be part of a team."

Kotchman makes grand debut against Mets

JUPITER, Fla. -- After a freak injury delayed his Spring Training debut, Marlins first baseman Casey Kotchman knocked a first-inning grand slam to right on the second pitch from Mets starter Jenrry Mejia on Tuesday afternoon.

The 30-year-old and nine-year veteran, who is in camp on a Minor League contract, sliced his left ring finger on Feb. 18, when he ran into a machine flinging infield popups that was located around home plate. Kotchman sprinted in from first and made the catch, but collided with the machine in the process. He received four stitches and scraped his left middle finger.

"I'm feeling OK, progressing, just trying to get into game shape," Kotchman said before the game. "I've been on my feet as much as I can just trying to get the swelling out and make sure it's not infected, and get healed up."

Kotchman started and batted sixth against New York after taking a few at-bats for the first time in six days in a simulated game on Sunday. He grounded out to second in the fourth. Matt Downs replaced him in the top of the fifth.

"It felt nice to just get out there with your teammates, get out and sweat a little bit, play the game and try to get into shape," said Kotchman after the game.

In the fourth inning, he caught Brian Bixler's infield popup.

"I'm glad I caught the infield fly without hitting the pitching machine," said Kotchman, who is expected to have the stitches out either late Tuesday or Wednesday.

Last season in 142 games with the Indians, Kotchman hit .229 with 12 home runs and 55 RBIs. In 2011 with the Rays, he batted .306 with 10 homers and 48 RBIs.

With projected starting first baseman Logan Morrison recovering from right knee surgery, Kotchman and several other players are looking to earn a spot on the Opening Day roster.

"You'd rather have it early than late, no doubt about it," Kotchman said. "It gives you plenty of time to get ready and get your body in shape. You obviously want to be out there. You want to see how [your teammates] go about it on the field. At the same time, you don't want to rush things too much. You just find that good balance."

Worth noting

• Top prospect Jose Fernandez will start the "B" game against the Cardinals at 10 a.m. ET on Thursday.