Miami Dolphins running back Knowshon Moreno is set to have an arthroscopic procedure on his knee and will miss the next four to five weeks, which may make him unavailable at the beginning of training camp.

The news was first reported by ESPN’s Adam Schefter.

The news on Moreno came on the same day the Dolphins lost Pro Bowl center Mike Pouncey for the next three months after he had surgery to repair a labrum injury in his hip.

Moreno has struggled in training camp to break through to the first-team. He’s battled knee problems in the past, most notably a torn anterior cruciate ligament several seasons ago. The latest issue with his knee is not the same one that had the torn ACL.

Moreno signed a one-year contract with the Dolphins and was expected to challenge Lamar Miller for the starting running back job. Last year in Denver, Moreno flanked Peyton Manning and ran the ball 241 times for 1,038 yards and scored 10 rushing touchdowns.