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02/22/12 6:51 PM EST

JJ throws impressive bullpen session

JUPITER, Fla. -- Throwing 10 minutes off a mound is hardly an indicator of how a season will play out, but for Josh Johnson it definitely represents an encouraging starting point.

The Marlins' 28-year-old ace threw his first bullpen session on Wednesday, Miami's first official day of Spring Training.

With all eyes on Johnson, who is recovering from inflammation in his right shoulder, the two-time All-Star cleared his initial hurdle.

"My arm felt great," the hard-throwing right-hander said. "It still won't feel the way I want it to until I throw some more 'pens. The strengthening keeps going up with the more I'm throwing."

Though Johnson's session was short, the way he was throwing immediately caught the attention of catcher John Buck.

"Right after, I went up to him and said, 'You feel good, huh?'" Buck said. "He said, 'Why?' I said, 'That was coming at me pretty easily.' I remember last year, when he was throwing, he was like touchy-feely, taking it easy."

Johnson felt that he was doing the same thing on Wednesday, getting a feel for his pitches. The difference from a year ago was the life on his fastball.

"It was heavy," Buck said of the impact of Johnson's velocity. "Even the first couple kind of handcuffed me, because I was expecting him just going through the motions like he did in his first few bullpens last year.

"As soon as I felt those first few pitches, I was like, 'He's feeling better.' I was kind of excited about that."

The Marlins have made it clear that they need Johnson to remain healthy if they are to have a serious chance of dethroning the Phillies in the National League East.

At 6-foot-7 and 250 pounds, Johnson is an imposing figure on the mound. The velocity on his fastball typically ranks among the top of any starter in the game, and his slider is among the best in the NL. Durability, however, has been a struggle.

Johnson made just nine starts and logged 60 1/3 innings in 2011. But when he pitched he was dominant, posting a 3-1 record with a 1.64 ERA, striking out 56 while walking 20.

He experienced tightness in his shoulder on May 16, against the Mets, and missed the rest of the season. The Marlins had been in contention through May but began to slide out of the race with a 5-23 record in June. The loss of Johnson was felt.

Johnson noted that his shoulder was a bit tight last Spring Training but that he was able to pitch through the mild discomfort.

Right now the shoulder feels strong, and he is scheduled to be back on the mound again on Friday.

"I've thrown nine bullpens or so, and I haven't even been sore yet," he said. "The next day I'd wake up and I couldn't even tell [I'd pitched]. Usually you feel that little bit of soreness, and you'd throw. Now it's like nothing. I'm hoping that continues. We're hoping the recovery process is to get that stuff out of there as quickly as possible."

The Marlins are not putting any restrictions on their ace in Spring Training, but they are closely monitoring him.

"That's the first time I've seen him throw live," manager Ozzie Guillen said. "I only care about JJ after he pitches. How he feels tomorrow. We have to really track [that] every day, [how] he feels -- not babysit him, but see how he feels every day. He felt pretty good today."

If Johnson is at full strength, the Marlins have a rotation they feel can compete with the best in the NL.

Johnson is projected to start on Opening Night, which is April 4 against the Cardinals at Marlins Park.

Mark Buehrle is expected to start the second game. Spring Training performance will largely determine the order of the final three rotation spots. Ricky Nolasco, Anibal Sanchez and Carlos Zambrano have a stronghold on those slots.

Though Johnson is being looked at to anchor the rotation, Buck notes that the depth of the staff also benefits the hurler.

"I think it works both ways for him," Buck said. "Obviously, you've got to have your No. 1 out there the whole year if you want your best chance to win. But I also feel that with the additions that we've made, that it's not completely on his shoulders now. You don't want to go without him. It's not all or nothing with Josh. This team is clearly good enough to survive without Josh, but I don't want that."

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.