Moustakas sustained the injury on a diving defensive play against the Mariners on July 28, then aggravated it while sliding in the Royals' series against Cleveland. Moustakas also was out of the lineup on Friday against Texas, while Yuniesky Betancourt got the start at third base in two of the three games against the Rangers.
Royals manager Ned Yost said that while Moustakas can play with the injury, as he did on Saturday, giving him days off would prevent him from being unable to play.
"It's a bone bruise. It's not a major issue. It's a playable thing, but it's going to be sore for a couple weeks," Yost said. "You just pick your opportunities to give him breaks when you can. It's something he can definitely play through. You don't want to get it to the point where it gets unplayable. Any time you can give him a break, it's going to be advantageous to him."