FORT MYERS, Fla. -- Mets manager Jerry Manuel was as thrilled as anyone when Fernando Martinez blasted a go-ahead three-run home run against the Red Sox on Wednesday, raising his Grapefruit League average to .538. But he did his best to ignore it.

The Mets are set at the corner outfield positions. And Manuel doesn't believe Martinez is strong enough defensively to play every day in center.

"The center-field part is very important to us right now," Manuel said. "We came in here with the mantra that we're going to catch the baseball, play good defense and that type of thing."

It is, of course, difficult to ignore the offense. Martinez has now whacked two doubles, two triples and three home runs, among seven other hits, in 26 Grapefruit League at-bats. He has slugged 1.115 and reached base at a .500 clip. And at 21 years old, he remains one of the organization's brightest offensive prospects.

But the Mets are focusing on defense.

"I would like to continue to see him in center field," Manuel said. "I think it gives him a different look. It also gives him some versatility."

Though Martinez has played plenty of center in the Minors -- and though he manned the position eight times with the big club last year -- he cannot come close to matching the defensive abilities of Angel Pagan or Gary Matthews Jr.

Outhitting or outslugging those two won't do him much good. The Mets will only take him on their roster if he proves adept enough to play every day in center. And he isn't likely to convince them of that this spring.

But still, it's hard to ignore what Martinez is doing with the bat, again and again and again.

"When I came up last year, I tried to do too much, because I didn't want to go back again," Martinez said. "This year, I'm just playing the game, relaxing and enjoying the game."