Source: Tom Brady's MRI negative

FOXBOROUGH, Mass. -- An MRI on the left knee of New England Patriots quarterback Tom Brady, who went down after an incomplete pass in 11-on-11 drills during a joint practice with the Tampa Bay Buccaneers on Wednesday, came back negative and he is considered day to day, a source with knowledge of the injury told ESPN NFL Insider Adam Schefter.

The Patriots will re-examine Brady in the morning, but a source told Schefter the quarterback is likely to practice Thursday.

A source told ESPN's Ed Werder that Brady "will be fine" and is expected to practice Thursday.

Video taken by a fan showed Bucs defensive lineman Adrian Clayborn push Patriots offensive lineman Nate Solder into Brady's leg just after Brady threw the ball. Brady immediately went down and grabbed his leg.

Patriots president Jonathan Kraft was not at the practice but heard what happened. In an interview with Boston sports radio station 98.5 The Sports Hub, Kraft said he made a phone call to check on Brady's status and was told that it "hopefully did not appear to be that bad."

"I understand from people who were standing out here it may have looked serious," Kraft said. "I don't have a definitive answer. And in classic [coach] Bill Belichick fashion, I will tell you a little bit more though, and just say I don't believe it's serious, but I do not know."

After limping to the sideline under his own power, Brady missed one play before rejoining and finishing the drill, completing three more passes. Following the drill, Brady huddled with Belichick, offensive coordinator Josh McDaniels and head trainer Jim Whalen, and it was determined that Brady would not continue to practice.

He jogged off the field with Whalen.

After practice, Clayborn told reporters he was bull-rushing Solder on the play on which Brady was injured, and that Solder fell back into Brady.

"You always have to stay away from the quarterback, but if you have a guy on his heels, my instinct is to keep going," Clayborn said.

Solder said he wasn't sure exactly what happened on the play.

"Anytime someone goes down, we worry about it," Solder said. "So we'll see what happened. I don't know at this point. ... There were a few different things that happened, so I'll have to see it [on film]."

Belichick was not available after practice, but Buccaneers coach Greg Schiano said he told his team not to touch the quarterback.

"Coach Belichick and I stressed to our teams: Let them throw the football," Schiano said. "Rush the passer, but go by them and don't get around them. I can't tell you [more] because I didn't see what happened."

Brady missed the 2008 season after tearing the ACL in his left knee in the first quarter of play in Week 1 against the Kansas City Chiefs.

Ryan Mallett is the Patriots' second-string quarterback, and Tim Tebow is No. 3 on the depth chart. The Patriots play the Bucs in their second preseason game Friday night at Gillette Stadium.