Mountcastle (forearm) is starting at first base and batting cleanup Friday at Kansas City, Roch Kubatko of MASNSports.com reports.
The 24-year-old exited Sunday's contest with a left forearm contusion after being hit by a pitch, but he's ready to play after taking the All-Star break to rest up. Mountcastle hit .255/.305/.447 with 14 homers, 14 doubles, 48 RBI and 39 runs in 83 games during the season's first half.