The Cubs placed Alzolay on the 10-day injured list Saturday with a left hamstring strain, Andy Martinez of Marquee Sports Network reports.
The strain is considered minor, but it shortened his poor outing Friday, when he allowed six runs on five hits and a walk in 1.1 innings. It's unclear how many starts Alzolay will miss while his hamstring recovers. Trevor Megill was recalled from Triple-A Iowa in a corresponding move Saturday.