Tennessee quarterback Justin Worley is out indefinitely after undergoing surgery on his right thumb.
Volunteers coach Butch Jones announced the severity of Worley's injury after Tuesday's practice and said he believes Worley has a torn ligament. Jones said Worley's return "could be (in) two weeks, it could be three weeks, it could be four weeks."
Knoxville radio station WNML had reported earlier Tuesday that Worley would miss about four weeks.
Worley's injury means freshman Joshua Dobbs will make his first career start Saturday when Tennessee (4-4, 1-3 SEC) plays at No. 10 Missouri (7-1, 3-1). Dobbs replaced an injured Worley in the second half of a 45-10 loss to No. 1 Alabama last week.
Worley has thrown for 1,239 yards with 10 touchdowns and eight interceptions this season.