"I didn't alter the ball in any way," Brady said at a press conference. "I have no knowledge of wrongdoing."
The NFL is investigating why game balls the Patriots provided for Sunday's AFC Championship Game were underinflated. ESPN, citing NFL sources familiar with the probe, reported that 11 of 12 game balls that the Patriots used on offense were found to be underinflated by about 2 pounds per square inch each.
A ball with lower inflation is said by some to be easier to grip and may give the passer a competitive advantage.
Brady said he picked the footballs he wanted to use five hours before the game, feeling the laces and the leather but not paying attention to the inflation level. The NFL mandates balls should be 12.5-13.5 psi.
"It's not like I squeeze the football," he said. "I grip the football."
Brady said he didn't touch the balls again until the game began. The referees inspect footballs about two hours before kickoff and deliver them to "ball attendants" who take them to the sidelines, according to NFL rules. The Patriots' opponent, the Indianapolis Colts, provided their own footballs.
Brady also said he couldn't tell any difference between the balls in the first and second halves.
Radio station WEEI in Boston reported
that the underinflated balls were discovered in the first half and replaced with properly inflated balls in the second half, when the Patriots expanded their lead over the Indianapolis Colts. The final score was 45-7.
Ball inflation may not be a problem at the February 1 Super Bowl game between the Patriots and the Seattle Seahawks. Michael Signora, the NFL's vice president of football communications, said Chicago Bears equipment manager Tony Medlin will oversee the game balls.
Dressed casually in a sweater and a wool hat, Brady seemed amused by the controversy at times during the 30-minute press conference.
Brady, 37, is the handsome face of the Patriots, one of the United States' most successful sports franchises. The team has won three Super Bowls, all with Belichick and Brady, and won its division, the AFC East, 12 times in 14 years.
His stardom reaches far beyond football fans, since he's married to model Gisele Bundchen and has worked as a model himself. His net worth is $120 million, according to Celebritynetworth.com
Though Brady himself has a clean image, suspicions of the Patriots remain because of a 2007 cheating incident -- called "Spygate" -- in which the team stole defensive signals from the New York Jets. Belichick was fined $500,000 and the NFL took away a first-round draft pick.
Some people are suspicious of Brady.
Speaking Thursday morning on CNN affiliate KTCK Sports Radio
, former Dallas Cowboys quarterback Troy Aikman said, "Its obvious Tom Brady had something to do with this. For the balls to have been deflated, that doesn't happen until the quarterback wants that to happen, I can assure you of that."
Hall of Fame coach John Madden told The Sports Xchange
he believed Belichick was clueless about the ball pressure, but "I can see -- and you hate to make examples of what you can see because that sounds like you are accusing someone -- but I can see that being between the quarterback and the equipment guy."
Though the NFL announced its investigation on Monday, Brady said nobody from the league has questioned him.
Brady said he didn't know anything about Deflategate until a Monday interview with WEEI, in which he said the idea of tampering with footballs is "ridiculous."
On Thursday, he said, "I was surprised as anybody when I heard Monday morning what was happening."
When a reporter directly asked Brady whether he was a cheater, the quarterback replied: "I don't believe so. I've always played within the rules."
He added that he doesn't have all the answers, but doesn't know of anybody in the Patriots organization who might have done something wrong with the ball.
"I don't know what happened over the course of the process with the footballs. I was preparing for my own job, doing what I needed to do," he said.
Belichick says he never has discussed the issue
Earlier on Thursday, Belichick said he was "shocked" to hear allegations that his team's footballs were underinflated.
He said that he's learned more about the football inflation process in three days than he has known or talked about in his 40 years in the league.
"In my entire coaching career, I have never talked to any player (or) staff member about football air pressure," the Patriots coach said at a press conference. "That is not a subject that I have ever brought up. To me, the footballs are approved by the league ... pregame, and we play with what's out there."
Belichick -- one of the most successful head coaches in NFL history with three Super Bowl rings and 211 regular-season wins -- insisted he had no explanation for how the footballs his team used Sunday might have gotten deflated.
But "in the future," Belichick said, New England's game balls will be inflated at high-enough levels -- so closer to 13.5 psi than 12.5 psi, when they may naturally drop to below acceptable levels -- "to account for any possible change during the game."
His comments come days after Indianapolis reporter Bob Kravitz
broke the news after Sunday's game that the NFL was looking into whether the Patriots used underinflated footballs during the AFC championship contest. The underinflation came to light on the field after Indianapolis Colts linebacker D'Qwell Jackson intercepted a pass thrown by Brady.
For all the talk by unnamed sources, the NFL's official statement on the controversy is succinct: "We are continuing our review and will provide information as soon as possible."
Deflategate is not the NFL's only scandal this year. The league established a six-game unpaid ban
for personnel who violate the league's policy on domestic violence after several players were arrested.