Farrell will take the mound in Cincinnati on Saturday, Carrie Muskat of MLB.com reports.
This will mark his first big-league start this season and just the second of his career. Farrell has appeared in 12 games out of the bullpen for the Cubs this season, posting a 3.63 ERA and 1.38 WHIP with a healthy 26:6 K:BB across 17.1 innings. The 27-year-old has made a handful of starts for Triple-A Iowa and hasn't been used since June 17, so he should be fully capable to pitch at least five frames if he's able to have a good day on the rubber.