Holliday fouled a 1-0 pitch from Nationals reliever Ryan Mattheus off his left shin in the eighth inning of Wednesday's 8-0 win, and he was replaced by pinch-runner Shane Robinson after hitting a two-run single.
"We have had this happen to him quite a few times through the season, whether it's hit by a pitch or foul ball," Matheny said. "He's tough."
Holliday hit .435 during last year's NL Championship Series, and the six-time All-Star is batting .333 (5-for-15) with a homer and three RBIs in this year's playoffs, entering Thursday's game.
"The guy has played just about every day for us," Matheny said. "Absolutely has the respect of the clubhouse for that, a guy comes in banged up and still finds a way not to just get in there, but to do something big for us."