Gronkowski immediately pounded the turf, writhing in obvious pain. The Patriots declared him out for the game shortly thereafter.
The injury is to the same knee that was reconstructed in January of 2014.
The Patriots might have dodged a worst-case scenario, however. NFL Media Insider Ian Rapoport reported Monday morning that the belief is the tight end suffered no structural damage in his knee. Further tests are slated for Monday, but his time out should be minimal.
Earlier in the game, Gronkowski had bypassed Shannon Sharpe on the career touchdown lists for tight ends, which means the 26-year-old has more touchdowns than any tight end currently in the Hall of Fame.
The Patriots lost elusive satellite back Dion Lewis in Week 9, playmaking receiver Julian Edelman in Week 10 and saw Edelman's replacement, Danny Amendola, leave with a knee injury in Week 11. Even as attrition began taking its toll on the AFC's best team, Patriots fans could rest assured that their team remained a Super Bowl favorite as long as Brady and Gronkowski escaped the wrath of the football gods.
Gronkowski's importance cannot be overstated. He has been the NFL's most valuable non-quarterback since entering the league in 2010, anchoring New England's run game and aerial attack.
The Patriots have averaged over 32 points through Gronkowski's 76 games, the highest mark for any player in NFL history.
If further resting reveals a more serious Gronkowski injury, the AFC is up for grabs.