Tom Brady doesn’t believe the New England Patriots had a single 20-year dynasty. Instead, the former quarterback sees it as two separate 10-year dynasties: one in which he won his first three Super Bowls with a core group of players, and another in which he captured his final three titles alongside a different cast. Still, despite winning three Super Bowls in his first four seasons, Brady had yet to experience what would become the most painful loss of his career in what could have been a dream season.

“In 2007, we were undefeated,” Brady said on Stick To Football. “We had probably the greatest football team ever. We lost to the New York Giants in the Super Bowl on some incredible plays the Giants made. One is called the helmet catcher guy. Eli Manning threw the ball in the middle of the field, and Jack jumped up. He was like the guy who never heard of, caught the ball, stuck it on the back of his helmet, fell backward, landed on the ground, and controlled the ball on his helmet.

“They had his other hand locked up, and they ended up scoring a touchdown, and we lost the game. We would have been 19-and-0, and we’d been considered, I think, the greatest football team ever. We lost that year. That was the most brutal loss of my entire career.”

The Patriots were chasing history. After becoming the first team to finish a 16-game regular season undefeated, New England reached the Super Bowl on February 3, 2008. The New York Giants, meanwhile, were underdogs, entering the playoffs as a 10-6 wild-card team. Still, Eli Manning and his unit prevented the Patriots from repeating what the Miami Dolphins did in 1972: To complete a perfect season.

The Patriots were already leading 14-10 late in the fourth quarter after Brady found Randy Moss for a 6-yard touchdown. However, Manning and the Giants had one final possession. With 1:15 left in regulation, and facing 3rd-and-5 from their own 44-yard line, Manning dropped back to pass, narrowly escaping a sack, and somehow broke free to launch a desperate throw down the middle of the field.

The pass traveled toward David Tyree, a receiver who had caught only four passes for 35 yards during the entire 2007 season. With Rodney Harrison covering him, Tyree leaped into the air and secured the ball with both hands. Harrison immediately swiped at the ball and dislodged one of Tyree’s hands. But the receiver pressed the football against the top of his helmet with his right hand while falling backward, and maintained the possession for a 32-yard gain. The grab was famously named the “Helmet Catch.”

Four plays later, Manning connected with Plaxico Burress for a 13-yard touchdown with less than a minute left, as the Giants ultimately won 17-14. New York completed one of the biggest upsets in sports history, denying Tom Brady and the Patriots a perfect 19-0 season. For Brady, things didn’t go well from there, as he tore his ACL the next season. He led the Patriots to another Super Bowl in the 2011 season, but lost to Manning once again.