Williams provides updates on Fister, Span, McLouth

Injured right-hander Doug Fister, who is on the 15-day disabled list with a right lat strain, threw a 50-pitch bullpen in Miami this afternoon. If he feels good tomorrow, the Nationals will work a simulated game into his upcoming rehabilitation schedule.

"Fifty pitches, and he was a little winded, he told me afterward, but physically he was good," manager Matt Williams said. "Everything felt good. He's progressing. It's a very good sign for him to go through that today and have no problems."

Williams isn't sure where a simulated game would take place, but said Fister will need to work through at least one before heading out on a minor league rehabilitation assignment.

"We've got to progress him like we would (in) spring training," Williams said. "He's done his two-ups now, he'll progress to that simulated game and we'll start him in those real games, monitor those pitches and see where he goes. But how close is he? He's as close as feeling good every time he goes out there, and that natural progression will take care of itself, whatever that is."

Center fielder Denard Span, who is on the seven-day concussion DL, took swings in the cage and on the field Monday. The Nationals were awaiting Span's meeting with a physician as part of the concussion recovery protocol when Williams met with reporters. Williams said Span needed to "get hot" and cool down as part of the evaluation, which includes a battery of concussion tests.

Because Span has previously dealt with concussion problems - they cost him a good deal of the 2011 season - the Nationals will tread carefully.

"Given his history, he's got that baseline, and he's got the extreme part of it, too," WIlliams said of Span. "It's about how he feels. The tests are designed to make sure they can't fake it. ...You got to take that first step before you take that second."

Outfielder Nate McLouth, who was pulled from Sunday's starting lineup after he tweaked his left knee during pregame workouts, is still "extremely sore," Williams said, but available to pinch-hit.

"Structually, it seems fine. ... There's no cause for concern in that regard. He just tweaked it. And it could be sore for a couple of days," Williams said.

So far, McLouth is not scheduled for an MRI, Williams added.