"I might need to check on him a little more," Johnson said of his 20-year-old left fielder. "He hadn't really been in the training room, and that's the good sign. But again, I'm not going to take any chances."
Harper missed Wednesday's game as a precaution after he recently iced his left knee, which caused him to miss 31 games this season. Desmond's blister, while also not serious, could cause the shortstop to miss more than one game.
"It's a big blister," Johnson said. "He got it from a lot of hitting, and when he slid headfirst one time, it just broke. … It was really looking bad [Tuesday] night."
Desmond played in 99 of the team's first 100 games. Entering Wednesday, he had played in more games than any Major League shortstop besides J.J. Hardy of the Orioles (102) and Jimmy Rollins of the Phillies (101).
"It helps because he's such a good player," reliever Tyler Clippard said. "He's come a long way, he's put in a lot of work to get where he's at, and we all see that, especially guys who've been around for a while, and we respect that. … He's out there every day, grinding it out."
With Desmond on the bench, Johnson shifted Anthony Rendon to shortstop and inserted Steve Lombardozzi into the lineup at second. Rendon had never started a Major League game at shortstop, but he said that he grew up playing the position in high school.
"It's easier really for a third baseman to play short than it is for a true second baseman to go over there," Johnson said. "But playing a new position at this level, I think he's doing great. Not only is he learning to play a new position, but the adjustments you have to make up here."
Tom Schad is an associate reporter for MLB.com. Follow him on Twitter @Tom_Schad. This story was not subject to the approval of Major League Baseball or its clubs.