VIERA, Fla. -- Nationals center fielder Nook Logan suffered a strained right groin against the Cardinals on Saturday afternoon. He is listed as day-to-day.

With the score tied at 2 in the bottom of the ninth inning, Logan singled to right field off Cardinals right-hander Josh Hancock. The ball slowly reached John Rodriguez, prompting Logan to consider taking the extra base. Logan took a wide turn and then suddenly fell to the ground between first and second. Rodriguez then threw the ball to first baseman Tagg Bozied, who put the tag on Logan for the second out of the inning.

"The ball wasn't hit that hard," said Logan. "It went by the first baseman and I was thinking, 'One out, try to get to second.' But [Rodriguez] got to the ball pretty quick. I had to get back to first. I was planning to go back. Unfortunately for me, I stretched my groin a little bit."

After the out was made, Logan was still laying on the ground. Assistant athletic trainer Michael McGowan came to his aid and was followed by manager Manny Acta. About two minutes later, Logan was able to get up on his own power and walk gingerly off the field and into the trainer's room.

Logan went so far as to say he didn't need to go to the hospital for an MRI and he would be back on the field in a couple of days, but the team may have other ideas. He gingerly walked on his own power into the clubhouse and talked to a group of reporters.

Logan claimed that the strained groin is not as serious as the left groin he strained while attending Copiah Lincoln Community College in Wesson, Miss. Logan said he didn't miss that much time while he was in school.

"I don't think an MRI is necessary," said Logan, who noted he will probably know more in a few days. "I felt like it was more of a scare. I felt a little grab. I felt a little pain right there, but 10 or 15 minutes after that, when the doctor checked me out, there was no swelling. That's good right now."

Acta was cautious when talking about Logan's injury, saying he wants to see how Logan responds to treatment over the next couple of days.

"We'll reevaluate him [Sunday]. It's the first day and a guy doesn't think it's serious until the next day, when he wakes up on it," Acta said. "We will not know until we get the results. We still have a week or so to go [before Opening Day]. It could be three days, it could be five, it could be two months. We don't know."

Acta said if Logan is not ready for Opening Day, Ryan Church will be the starting center fielder, while Kory Casto and Chris Snelling battle it out in left field.

With Church in center, the Nationals may be at disadvantage defensively. Church has played 73 games in center field during his career, but he had problems playing the position at Robert F. Kennedy Stadium. He often lost sight of balls hit directly at him, having them sail over his head for base hits. While Church is not a slow runner, he does not have Logan's range. Church is better suited as a corner outfielder.

Church acknowledged the he had problems in center field at RFK and plans to work hard to correct it.

"RFK is a spacious yard," Church said. "It's one of those things where you keep on working and keep taking balls off the bat during batting practice. Every yard is different. I can still remember the balls that I misplayed. I didn't see them off the bat right. If I play there, I may have to play two or three steps deeper. The biggest thing for me is to work hard at it."

Snelling has been a pleasant surprise this spring, hitting .270 with three home runs and 13 RBIs, which ranks second behind third baseman Ryan Zimmerman. Snelling came into camp as a reserve, however general manager Jim Bowden said Sunday that Snelling is competing for a starting spot in left field. On Friday, the Nationals received a scare when Snelling suffered a left knee contusion in a collision with Tigers catcher Steve Torrealba, but Snelling played in Saturday's game against the Cardinals.

Casto has become a favorite with the team's front office. According to sources, even before the injury to Logan, there were some in the organization who felt that Casto should be the everyday left fielder because of his patience at the plate. Casto is 11-for-36 (.324) with six walks.

Even Acta went so far as to say that Casto is now being considered for a reserve role on the big-league team. The team likes the way Casto has come off the bench and delivered in clutch situations. Before Saturday, Acta kept saying that Casto would play every day either in the Major or Minor Leagues and was not being considered for a bench role.

Before the Logan injury, there also was a possibility that Casto could be sent down because he has options. Church and Snelling are out of options, and it's doubtful they will be placed on waivers to make room for Casto.

"We have not made any final decisions, but I know Casto deserves to be on this team," Bowden said.