The Chicago White Sox placed All-Star right-hander Shane Smith on the 15-day injured list on Saturday due to a sprained left ankle.
The move is retroactive to Wednesday.
It wasn't immediately known when Smith sustained the injury. The rookie last pitched in Tuesday's All-Star Game when he faced two batters in the eighth inning, hitting Eugenio Suarez with a pitch before retiring James Wood on an inning-ending grounder.
Smith, 25, is 3-7 with a 4.26 ERA and 81 strikeouts in 18 starts for the White Sox. He is the franchise's first rookie pitcher to make the All-Star team.