KANSAS CITY, Mo. (WDAF) — Travis Kelce and Taylor Swift caused an immense whirlwind after the music superstar was spotted at Arrowhead to watch the tight end play on Sunday.

In fact, Kelce saw a nearly 400% increase in jersey sales after Swift’s appearance, Fanatics told TMZ Sports.

“Yesterday, Travis Kelce was one of the top 5 selling NFL players and saw a nearly 400% spike in sales throughout the Fanatics network of sites, including NFLShop.com,” Fanatics said.

Swift’s impact cannot be understated. While Kelce is one of the most popular players in the league, prior to Sunday’s game against the Bears, Kelce was outside the top 10 in jersey sales.

The pairing has caused quite a spectacle—especially after being seen leaving the game together—not just across Kansas City, but all over.

In a video captured by WGN’s Jarrett Payton, Kelce and Swift could be seen walking side by side after the Chief’s 41-10 blowout win against the Chicago Bears. The video has gone viral and as of Monday morning, had over 9 million views.

It came after weeks of rumors that the tight end is dating the music superstar.

Travis Kelce discussed the rumors on his podcast, “New Heights,” with his brother, Philadelphia Eagles center Jason Kelce.

“I threw the ball in her court and told her, ‘I’ve seen you rock the stage in Arrowhead. You might have to come see me rock the stage in Arrowhead and see which one’s a little more lit,’” he said at the time.