Curtiss, a sixth-round pick by the Twins in 2014, will join the team in Chicago. To make room, Minnesota designated right-hander Tim Melville for release or assignment.
Curtiss split time in Double-A and Triple-A this season, excelling at both levels. He was promoted to Triple-A in late June after logging an ERA of 0.72 while converting on 13 of 13 save opportunities for Double-A Chattanooga.
In 24 1/3 innings for Triple-A Rochester, Curtiss has allowed just 11 hits and five earned runs while fanning 33 hitters and walking 10. He recorded six saves in seven opportunities.
Melville made his Twins debut in Game 1 of the doubleheader against the White Sox on Monday. He allowed five runs and four hits in 3 1/3 innings while whiffing four hitters. Melville’s velocity reached the mid-90s but he struggled with control, walking three Chicago batters on the day.