The league-leading Toronto Raptors have been dealt a significant blow to their frontcourt rotation.

Center Jonas Valanciunas will be in a cast for at least four weeks after undergoing surgery on his injured left thumb, the team announced Thursday.

The towering Lithuanian center dislocated his thumb during the second quarter of the Raptors' 113-93 win over the Golden State Warriors on Wednesday night in Oakland.

The 26-year-old has averaged 12.8 points and 7.2 rebounds in just 18.8 minutes per game, mostly off the Raptors' bench. He's currently scoring at a career-best 59.3 effective field-goal percentage.

The Raptors have already called in the reinforcements, calling up man Chris Boucher, the G League's leading scorer. In 14 appearances with the Raptors 905, Boucher has averaged 29.6 points, 11.6 rebounds, and 4.6 blocks per game, emerging as one of the top talents in the development system this year.

Toronto has enjoyed immense regular-season success to date. With a 23-7 record, the Raptors currently sit 3.5 games ahead of the second-seeded Milwaukee Bucks and Philadelphia 76ers in the Eastern Conference.