Williams said no MRI has been done yet, but McLouth's knee is getting better. If Monday marked the final game of the season, he could've played.
"Nate's still sore, really sore today, so they're treating it," Williams said. "They're making sure that when he does get back, that it's good. … It could've pinched something in there to make it sore. Structurally, everything checks out fairly well. There's no cause for concern in that regard. He just tweaked it. It could be sore a couple of days."
• Nationals center fielder Span, currently on the seven-day concussion disabled list, took swings before and during batting practice on Monday. Doctors planned to check on him afterward.
Span sustained the concussion when he collided with Braves second baseman Dan Uggla while running the bases Friday.
"He's going to come back in [Tuesday] and do some more," Williams said. "We may on the last day here send him back to see the doc to make sure prior to us getting home. That's still up in the air."
Christina DeNicola is a contributor to MLB.com. Teddy Cahill is a reporter for MLB.com. Follow him on Twitter at @tedcahill.