Freeman left Saturday night's exhibition game with the Kansas City Chiefs about midway through the first quarter after leading the offense to a field goal.
The team said the current expectation is that Freeman will be ready to open the regular season on Sept. 12 against Cleveland. He should be able to return to practice well before the start of the regular season, but it's unlikely he'll play in the final two preseason games.
The second-year pro appeared to hit his hand as he followed through on a pass intended for tight end John Gilmore on second-and-5 from the Chiefs 13. He threw another incompletion on third down to end his team's first offensive possession, then walked to the sideline holding his right thumb.
Freeman remained on the sideline flexing his right hand when backup Josh Johnson took over on the next drive. He had been expected to play 12 to 15 snaps.
Tampa Bay is very thin at quarterback behind Freeman. Johnson is the backup and Rudy Carpenter is the only other quarterback on the roster.
Pat Yasinskas covers the NFC South for ESPN.com. Information from The Associated Press was used in this report.