Tebow left practice without speaking with reporters.
"Anytime anybody, especially a teammate, goes down it's a dark cloud. It's unfortunate," Patriots running back Shane Vereen said. "He went back out there, but we'll see."
Running back LaGarrette Blount was optimistic.
"He walked off," Blount said. "I'm sure he's cool. I'm sure he's fine."
But shortly before Blount spoke, a black helicopter landed on a field adjacent to the one where Brady was injured. Cameramen, apparently concerned that Brady might be airlifted to a hospital, rushed to record the landing.
"The helicopter has nothing to do with Tom," Patriots owner Jonathan Kraft said on WBZ-FM.
Tampa Bay coach Greg Schiano said he and Belichick stress to their players to rush the passer but let him throw the football and go past him.
"I didn't get to see" the hit on Brady, Schiano said. "I saw him laying there afterward. ... I hope he's OK."
Losing Brady would leave the Patriots without a proven starting quarterback. Mallett has thrown just four passes in his first two seasons and has been inconsistent during training camp. Tebow signed as a free agent on June 10 and has struggled with his throwing mechanics, a problem he's had since being drafted by the Denver Broncos in the first round in 2010.
"The big thing is just his familiarity with the offense, the way we do things — the play calling, the reads, formationing, just general things we do," Belichick said of Tebow. "The quarterback has to have a good understanding of all that. The more you do it, the more you get comfortable with it and the better you can execute it. I think that's no different, really, than any other young quarterback or quarterback coming into a new system."
In the Patriots' 31-22 exhibition win over the Philadelphia Eagles on Friday night, Mallett completed 9 of 18 passes for 97 yards. Tebow went 4 for 12 for 55 yards with three sacks and ran four times for 31 yards.
Brady completed 7 of 8 passes for 65 yards and one touchdown and left after the first two series.
AP NFL website: www.pro32.ap.org
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