PHILADELPHIA -- Cristian Guzman's left thumb is still not 100 percent, but the Nationals' shortstop isn't letting that keep him off the field.

Guzman, who has been bothered by a sore left thumb since the first week of July, started at shortstop and hit in the No. 2 hole for Thursday night's series finale against the Phillies. It was the 30-year-old switch-hitter's first start since Aug. 13.

"We're going to be kind of careful from now on," manager Manny Acta said. "This doesn't mean he's going to be out there every single day. He's wearing some thumb guards and stuff to try to help him out. He's feeling a lot better, especially from the right side. We'll see where this takes us today."

During August, the shortstop has struggled, hitting .172 (5-for-29) in nine games. Guzman, who leads the team with 136 hits, has seen his average drop from .317 on July 11 to .294.