Nook Logan suffered a potentially serious right groin injury during the ninth inning of Saturday's game against the Cardinals, one that may keep the Nationals' center fielder from starting on Opening Day.

With one out in the bottom of the ninth of a 2-2 game, Logan singled to right and made a wide turn around first. He then tried to stop in his tracks and retreat back to the base but crumpled in a heap and remained on the ground for several minutes. Logan walked off the field under his own power and after being examined by team trainers expressed optimism that the injury is not serious.

"It was more of a scare," he said following the Nationals' 4-2, 10-inning loss. "I just felt a little grab, a little pain right there. But 10, 15 minutes after that when the doc checked me out, there was no swelling, so that's good right now."

The Nationals have no plans to have Logan undergo an MRI, but he'll be re-examined at Space Coast Stadium tomorrow morning. Until then, they won't have a better idea of the severity of the injury.

"We won't know yet until we get the results," manager Manny Acta said. "We've still got about a week or so to go. It could be three days, it could five, it could be two months. We don't know."

If Logan isn't ready to return by Opening Day, Acta said Ryan Church would be his starting center fielder, and either Chris Snelling or Kory Casto would start in left.

Meanwhile, Nationals ace John Patterson suffered from dehydration before yesterday's game, was given an IV and was sent home. Patterson, who complained of feeling tired by the end of his four-inning start Friday, is not expected to miss his final exhibition outing Wednesday or his Opening Day start against the Marlins.