Rolison will work as the Cubs' opening pitcher Sunday versus Milwaukee, Bruce Levine of 670TheScore.com reports.
Rolison has one opening appearance so far this season, retiring all four batters he faced against the Giants on June 13. He's tossed fewer than two frames in each of his 10 outings so far in June, so the left-hander presumably won't work deep into Sunday's matchup. The Cubs haven't designated a bulk reliever to enter the game behind Rolison, though Bryse Wilson had recently been serving as a starter at Triple-A Lehigh Valley in the Phillies organization before the Cubs scooped him up off waivers Wednesday.