Siemian (shoulder) is believed to have suffered an AC joint sprain in his non-throwing shoulder, NFL.com's Ian Rapoport reports.
Siemian was removed from Sunday's game in Tampa Bay during the first half and never ended up returning, but it was reported that he could've rejoined the contest in the event of an emergency. If the initial diagnosis is confirmed, Siemian could potentially avoid any missed time beyond Sunday, as he can presumably play with his left shoulder at less than full strength. First-round selection Paxton Lynch filled in capably, completing 14 of 24 passes for 170 yards and a touchdown in a 27-7 win over Tampa Bay.