TAYLOR SWIFT, a guest of Kansas City Chiefs tight end Travis Kelce (87), cheers during the game at MetLife Stadium. —ROBERT DEUTSCH-USA TODAY SPORTS

POP megastar Taylor Swift traveled to New Jersey on Sunday night to watch Travis Kelce and his Kansas City Chiefs take on the New York Jets, as rumors about the pair’s relationship send the National Football League’s (NFL) ticket sales and television viewership soaring.

NBC’s cameras showed Ms. Swift in a luxury box with several other celebrities, including Hollywood actors Ryan Reynolds, Hugh Jackman, and Blake Lively. As the Chiefs scored the first touchdown of the game — running back Isaiah Pacheco, not Mr. Kelce, crossed the goal line — Ms. Swift was seen celebrating in the suite.

Unlike last week, when she sported a red-and-white Chiefs jacket to watch Mr. Kelce’s team defeat the Chicago Bears in Missouri, Ms. Swift — who lives in New York City — wore a black top and leather jacket in the more hostile environs of the Jets home stadium.

Ms. Swift’s appearance, in addition to fueling further rumors about her romance with the Chiefs’ star tight end, is sure to deliver another marketing blessing to the NFL.

Jets ticket sales for their game against the Chiefs soared after Ms. Swift’s appearance at the Chiefs’ last game, with sales in a single day more than doubling the previous record for this season, according to StubHub, a ticket resale platform. Sunday’s game was the second-highest selling game of the NFL season after the season opener, Stubhub said.

The cheapest nosebleed seat tickets for Sunday’s game in East Rutherford, New Jersey, were going for $81 on Sunday afternoon, while resale tickets at the lower level cost close to $9,000.

Ms. Swift, 33, has sold out football stadiums across the United States over the last several months as she embarked on the domestic leg of her international, recordbreaking Eras Tour including MetLife Stadium, where her three sellout shows in May drew more than 200,000 fans in all. She sent her cultlike fanbase of “Swifties” into a frenzy last week when she made a surprise appearance in Mr. Kelce’s suite at the Chiefs’ home game in Kansas City.

Advertisements for the upcoming Eras concert film, opening in theaters this month, ran on NBC ahead of the game broadcast. Gambling sites offered several Swift-themed bets before kickoff; FanDuel users could bet against Mr. Kelce scoring a touchdown, a wager titled the “FriENDZONE.”

Ahead of Sunday’s game, Sunday Night Football on NBC posted a promotional video on X with Swift’s song “Welcome to New York” playing in the background and the caption, “Taylor Made for Sunday Night.”

When Swift showed up at the Chiefs’ game on Sept. 24, viewership among women ages 18-49 — Ms. Swift’s prime fan demographic — spiked 63% week-over-week.

The two have played coy on the nature of their relationship. Mr. Kelce spoke briefly about Ms. Swift this week when his brother, Jason, who plays for the Philadelphia Eagles, jokingly asked him on their podcast: “How’s it feel that Taylor Swift has finally put you on the map?”

“Shout out to Taylor for coming through and seeing me rock the stage,” said Mr. Kelce, who described her as looking “amazing” and dubbed Ms. Swift’s enthusiasm during the game and the excitement of Chiefs fans at seeing her there as “absolutely hysterical.” — Reuters