Thompson will start Saturday's game versus the Royals, Meghan Montemurro of the Chicago Tribune reports.
Thompson was reported as Saturday's expected starter earlier in the week, and manager Dave Ross confirmed the right-hander will be promoted from Triple-A Iowa to pitch. The 26-year-old posted a 2.21 ERA, 1.28 WHIP and 43:22 K:BB over 40.2 innings as a reliever for the Cubs earlier this season, but he's been stretching out as a starter at Triple-A since being demoted in late July. The right-hander didn't surrender a run and allowed only five hits over four outings during his brief time in the minors, and he'll attempt to carry over that success to the majors as the rebuilding Cubs give him a look in the starting rotation.