Manuel had been working back into practice this week following meniscus surgery on his left knee on August 18. He was out of the lineup for two weeks before returning to the practice field in a limited capacity on Sunday; he then practiced in full on Monday. Evidently, his knee held up well over those two days, and he'll take the first-team reps for the rest of the week.
Jeff Tuel, the rookie undrafted free agent out of Washington State that became a household name last week while Manuel was still recovering, is the only other quarterback on the active roster and will therefore serve as Manuel's backup on Sunday.
Manuel took part in just two preseason games this season, completing 26-of-33 passes for 199 yards with two touchdowns and no interceptions in the rough equivalent of three quarters of playing time. Now, the first-round draft pick will go toe-to-toe with Tom Brady in his first NFL start on home turf at Ralph Wilson Stadium.