Ian Rapoport of NFL.com noted head coach Bruce Arians said X-rays and tests revealed it was a "tiny fracture" that impacted the way he gripped the ball, but Winston was able to return and finish the victory.
The Florida State product has been relatively durable throughout his career even though he missed time in 2017 with a shoulder injury on his way to 13 games. It marked the first time in his early career he missed a game after playing all 16 contests in each of his first two seasons.
He was also suspended and benched in 2018 and appeared in 11 contests.
Winston threw for more than 4,000 yards as a rookie and second-year signal-caller but has struggled with interceptions throughout his career. He entered the 2019 campaign with 58 picks in 56 games, including the 14 he threw last year. He also threw for a career-low 2,992 yards and 19 touchdowns last season.
He has 23 picks this year after throwing three more Sunday.
The Buccaneers would turn toward Ryan Griffin if Winston is forced to miss time. Griffin had yet to appear in a regular-season game entering the 2019 campaign and was pushed into backup duty when the Buccaneers put Blaine Gabbert on injured reserve in September.
Griffin went 2-of-4 for 18 yards in relief against the Colts.