Indianapolis Colts quarterback Anthony Richardson suffered a right shoulder injury in the first half of Sunday's 23-16 win over the Tennessee Titans and did not return.
NFL Network Insider Tom Pelissero reported that the initial diagnosis of Richardson's shoulder injury is an AC joint sprain and he will undergo an MRI for a further assessment, per a source.
The X-rays done on Richardson's shoulder after the game came back negative, NFL Network Insider Ian Rapoport reported, per a source.
Richardson was injured in the second quarter at the end of a four-yard scramble, landing on his right shoulder as Titans linebacker Harold Landry made the tackle.
The Colts rookie QB went into the blue medical tent before walking to the locker room, heavily favoring his right arm. Indianapolis initially deemed Richardson as questionable to return before ruling him out upon its first offensive possession after halftime.
Gardner Minshew entered the game for Richardson with the Colts ahead of the Titans, 10-6. The veteran backup proceeded to lead the Colts into the red zone, but an incompletion to tight end Kylen Granson on fourth-and-1 from the 5-yard line ended a fruitless drive.
The Colts never relinquished the lead following Richardson's exit, holding off their AFC South foe for the victory. Minshew finished completing 11 of 14 passes for 155 yards.
Richardson completed 9 of 12 passes for 98 yards and added five rushing yards before exiting the game.
Sunday marked the third game in which Richardson has not finished due to injury.
At the end of the Colts' Week 1 loss to Jacksonville, Richardson missed the final three plays due to what was described as knee soreness. Richardson was ruled out of Week 2's win over Houston in the first half after self-reporting concussion-like symptoms following a touchdown run, an injury that eventually led to him missing Week 3 as he remained in the league's concussion protocol.