Riggleman said giving Dunn a day off was planned for several days. The skipper said third baseman Ryan Zimmerman will get the day off Sunday, with Willie Harris getting a start.
"It's a combination of getting Alberto a game and giving Adam a day off," Riggleman said. "I prefer to do it on the road than at home, because I know our fans would come out every day to see Ryan and Adam. I have to take this opportunity to get Gonzo in the ballgame. Alberto is a ballplayer. I can put him anywhere."
It will be the first time in his professional career that Gonzalez will play first base. He doesn't own a first baseman's glove, so he will use Dunn's. He started practicing at the position about a month ago on the suggestion of Tim Foli, the senior assistant to general manager Mike Rizzo.
Besides first base, Gonzalez has been working out in the outfield. Gonzalez said he is willing to play those positions to get more playing time. Entering Saturday's action, Gonzalez is 23-for-78 (.295) with three RBIs.
"I feel good. I feel happy that I can play," Gonzalez said. "I have been practicing everywhere."