Ethier left Thursday night's game after six innings with light tightness in his left quad, and was at times what manager Don Mattingly characterized as "heavy-legged."
On Friday, Mattingly downplayed the calf tightness, but still wanted to give Ethier a day off.
"He was generally sore as that game went on. He could have played last night, and he probably could have played today. But we didn't want him to go over the hill," Mattingly said. "If we can buy him a day today, hopefully he'll play the next couple of days. We expect him to be in the lineup tomorrow."
The Brewers start right-handed pitchers all weekend, with Jimmy Nelson on Friday night, Taylor Jungmann on Saturday, and Kyle Lohse on Sunday.
Ethier has played in 79 of 87 games this season, including 62 starts. With 263 plate appearances, he is on pace for 490 PA on the season, 110 more than he had in all of 2014.
Alex Guerrero gets a rare start in place of Ethier in left field, Guerrero's first start in nine days, and just his second start in the last 13 games. Guerrero is hitting .250/.275/.507 with 10 home runs in 160 plate appearances this season, but is currently mired in slumps of 0-for-12 and 3-for-30.