Busch is out of the lineup for Sunday's game against the Pirates.
The lefty-hitting Busch had started each of the Cubs' first 10 games of May and the Pirates are bringing a lefty (Bailey Falter) to the hill Sunday, so Cubs manager Craig Counsell likely viewed it as an optimal time to give the 26-year-old the day off. Patrick Wisdom will check in for Busch at first base and bat fifth.