The Chicago Cubs have moved Carlos Villanueva to the bullpen and promoted Jake Arrieta to start on Friday.
Chicago acquired Arrieta from the Baltimore Orioles on July 2.
"We want (pitching coach Chris) Bosio and (bullpen coach) Lester (Strode) to get a get a grip on (Arrieta)," Dale Sveum said. "We want him to pitch here and see what we got."