1860 Munich striker Kenny Cooper has undergone surgery to repair damage from a training injury to his right ankle and is expected to be on the shelf until October.
The 25-year-old U.S. international suffered the setback to his lateral malleolus, the lowermost tip of the fibula, on Thursday.
"For six weeks, he cannot do anything and then he will start rehab," 1860 press officer Robert Hettich told MLSsoccer.com. "We hope that he will be back in three months. It was very shocking because it was the first training session and nobody knows exactly how it happened. He was in a duel."
Last season, Cooper bagged three goals in 12 league matches for the Lions before heading out on loan to Championship side Plymouth Argyle in January.