Sources: Thumb surgery sidelines Oklahoma State's Spencer Sanders

Oklahoma State quarterback Spencer Sanders will miss the rest of the regular season after thumb surgery this week, sources told ESPN on Thursday.

Sanders suffered the injury on a pass attempt last Saturday, when his right hand hit an opposing player's helmet on a follow-through in a 31-13 home win over Kansas. His backup, Dru Brown, replaced him and threw a 43-yard touchdown pass in the third quarter.

Brown should start Saturday as the No. 21 Cowboys (7-3) take on the West Virginia Mountaineers (4-6) in Morgantown, West Virginia.

Sanders, a redshirt freshman, has thrown for 2,065 yards and 16 touchdowns. He has struggled with interceptions, throwing 11, but has thrown only two in the Cowboys' current three-game winning streak. Sanders has also rushed for 625 yards, second on the team to the nation's leading rusher, Chuba Hubbard (1,726).

Sanders rebounded from his worst start, a 45-27 home loss to Baylor Oct. 19, engineering consecutive wins over Iowa State, TCU and Kansas. Against the Bears, he threw for just 157 yards and accounted for three turnovers.

Brown, a transfer from Hawai'i, was the primary backup last season to Cowboys starter Taylor Cornelius, while Sanders redshirted. He started two seasons with the Warriors, throwing for 5,273 yards and 37 touchdowns before his transfer.

In primarily late-game duty for the Cowboys, Brown has thrown for 223 yards and three touchdowns this season. One big difference between the two quarterbacks might be Sanders' explosiveness as a runner. Sanders was a significant complement to Hubbard in the run game for a team that is averaging 46.5 carries a game.

Brown is mobile, however, if not as explosive as Sanders. In 2016, with Hawai'i, he ran for 306 yards and four touchdowns on 88 carries.

On Monday, in his weekly news conference, Oklahoma State coach Mike Gundy spoke highly of Brown for patiently waiting his turn through nearly two seasons in Stillwater.

"We were pleased with Dru. He has been a great illustration of the culture at Oklahoma State," Gundy said. "I mentioned it after the [Kansas] game -- he was a captain in that game because of all of the hard work and effort he has put in, and the commitment he has had to our program. We enjoy seeing him have success, and he came out and played well."

Oklahoma State closes the regular season Nov. 30 at home vs. No. 9 Oklahoma in the annual Bedlam Series game.