The surprise attendance of pop superstar Taylor Swift at Sunday's Kansas City Chiefs game also brought an unexpected surge in sales of Chiefs' tight end Travis Kelce's jersey, according to sports retailer Fanatics.

"Yesterday, Travis Kelce was one of the top five selling NFL players and saw a nearly 400% spike in sales throughout the Fanatics network of sites, including NFLShop.com," said a spokesperson for Fanatics, the NFL's official e-commerce partner.

The singer was shown cheering on the Chiefs during the FOX Sports broadcast, dressed in a red and white team jacket. She appeared to be sitting next to Donna Kelce, the player's mom, chatting and laughing throughout the game at Arrowhead Stadium in Kansas City.

Swift's show of support comes after weeks of speculation — by various NFL broadcasters and the vast majority of Swifties — that she and Kelce are dating, though the two have not publicly confirmed any romantic link.