Boston Celtics forward Daniel Theis is bound to undergo a season-ending meniscus surgery after suffering a tear in his left knee, according to Shams Charania of Yahoo Sports.

The German international has proved to be a key piece off the bench, making the news yet another downer for a team with championship aspirations.

Theis shined during the EuroBasket play last summer, showcasing plenty of potential as a hustling big man with range and a knack for good positioning instinct at both sides of the floor.

The 25-year-old averaged 5.3 points and 4.3 rebounds through a limited 14.8 minutes per game in a consolidated rotation, but proved to be a spark plug defensively with his shot-blocking ability (0.8 blocks per game) and his offensive rebounding (1.4 per game) off the bench.

Theis logged three starts in 63 games for the Celtics during his rookie season, which will come to an abrupt end following his surgery.