The Kansas City Chiefs win over the New York Jets on Sunday was the most watched Sunday show since the Super Bowl in February, attracting an average of 27 million TV viewers, including millions of teenage girls who tuned into the game attended by pop star Taylor Swift, NBC Sports said on Monday.

A rumoured relationship between Swift and Chiefs tight end Travis Kelce has sent interest sky-rocketing in Super Bowl champion Kansas City. Sales of Kelce's jersey surged after Swift's appearance at his Week 3 home game and it was rumoured she would be attending the New York-based game.

Swift was spotted in luxury box digs at MetLife Stadium in East Rutherford, N.J., watching the Chiefs eke out the nail-biting victory, as fans once again reveled in her appearance on social media. Several actors were seen in the box as well, including Canadian Ryan Reynolds and his wife Blake Lively, and Hugh Jackman.

Viewership among teen girls aged 12-17 spiked 53 per cent from the season-to-date average for Sunday Night Football, part of an approximate increase of more than two million female viewers, according to an NBC Sports release.

The Sunday night game, won by Kansas City 23-20, was up 22 per cent overall from last year's Week 4 prime-time affair across network NBC and digital platforms.

It fell short of being the most viewed game of the season. The NFL season opener — played on a Thursday between the Chiefs and the Detroit Lions — attracted 27.5 million viewers.

The Chiefs, who extended their record this season to 3-1 with the win, next play the Minnesota Vikings on the road on Sunday.