Shirtless Jason Kelce cheers on Travis, Chiefs with Taylor Swift after taking pregame shot with Bills Mafia

Jason Kelce was in Buffalo to support his brother, Travis, and the Kansas City Chiefs.

But he didn't turn down a good time with the Buffalo Bills faithful. Kelce partied with Bills fans pregame, than let loose in a suite with Taylor Swift as his brother's Chiefs won a 27-24 thriller to advance to the AFC championship game.

The Philadelphia Eagles' All-Pro center showed up early to the divisional-round showdown and made his way to one of the many Bills tailgates, where he was offered to take a shot out of a bowling ball.

Kelce obliged.

Everyone was happy. Kelce traded high-fives with Buffalo fans, who screamed his name and cheered on his revelry. What a scene.

But fear not, fans of the Kelce brothers. Jason hadn't turned on Travis, and he wasn't there to support the Bills on the field. He was later seen at Highmark Stadium next to Taylor Swift and sporting Chiefs colors. His allegiance Sunday was clearly with his brother.

In fact, when Travis scored a second-quarter touchdown, Jason howled in delight outside the open window of the box. He did so with a beer and without a shirt. The temperature in Buffalo was 21 degrees at the time.

He then jumped out the window into the stands to revel among the Bills fans. Most did not appear to appreciate his presence.

Jason remained shirtless and continued to drink beers during Travis' second touchdown catch, which gave the Chiefs a 20-17 lead in the third quarter. This time, he ceded the foreground to Swift.

For Eagles fans, none of this is particularly palatable. Instead of playing in a divisional-round playoff game with Philadelphia, Jason was watching one from a luxury box after the Eagles were eliminated from the postseason last week in the wild-card round.

They certainly don't like seeing Jason wearing the colors of the Chiefs team that vanquished their squad in last season's Super Bowl. But family comes first, and Jason came through for his brother Sunday — and had a good time along the way.