The Kansas City Royals on Monday placed starting pitcher Danny Duffy on the 15-day disabled list.
Duffy departed Sunday's 9-1 win over the White Sox with elbow tightness. He retired two batters and walked Gordon Beckham in the bottom of the first inning before leaving.
An MRI later Monday revealed a torn left ulnar collateral ligament (UCL). Duffy will get a second opinion.
The 23-year-old lefty is 2-2 with a 3.90 earned run average in six starts this season.
Kansas City replaced Duffy on the roster by calling up Nate Adcock from Triple-A Omaha. Adcock pitched to a 1-1 record with a 4.39 ERA over 27 games with the Royals in 2011 and 2012, including three relief appearances this season.