Florida starting quarterback Graham Mertz’s season is over after sustaining a knee injury in Saturday’s loss to No. 11 Tennessee, CBS Sports reported Monday.Mertz went down with a non-contact injury in the third quarter after throwing a 13-yard touchdown pass to Arlis Boardingham. The redshirt senior landed awkwardly after the throw and reached for his leg before limping to the sideline.He did not return to the game and was seen on crutches. True freshman DJ Lagway replaced Mertz.Gators coach Billy Napier said after the game that Mertz sustained a lower-body injury and would undergo testing.Mertz completed 11 of 15 passes for 125 yards and a touchdown for Florida before the injury. Lagway was 9-of-17 passing for 98 yards with a touchdown and an interception in the Gators’ 23-17 overtime loss to the Volunteers.