Michigan State basketball is undefeated and has tied the school record for best start ever at 12-0.

But a serious blow was dealt on Monday.

Denzel Valentine will miss two to three weeks due to a knee injury, head coach Tom Izzo announced at his weekly press conference. Valentine underwent arthroscopic surgery Monday morning.

Izzo said Valentine injured the knee in practice Sunday evening.

Valentine is obviously the Spartans' leader. He's top on the team in points (18.5), rebounds (8.2), assists (7.1), steals (1.0) and minutes (30.6) per game.

The former Lansing Sexton Big Red is No. 8 nationally in assists per game

Izzo said Valentine's duties will fall to Eron Harris. Harris is averaging 7 points, 2.7 rebounds, and 2.3 assists per game while logging an average of 16.3 minutes per night. The junior is in his first season playing at Michigan State after sitting out last season once he transferred from West Virginia.

If Izzo's timeline is correct, then a worst-case scenario suggests Valentine would be back in time for MSU's home game versus Iowa on Jan. 14--that would be three weeks. In that case, Valentine would miss five games: Tuesday vs. Oakland at the Palace of Auburn Hills, Dec. 29 at Iowa, Jan. 2 at Minnesota, Jan. 7 vs. Illinois, and Jan. 10 at Penn State.