The Chiefs tight end traveled to Argentina last month to see Swift perform

Taylor Swift (right) joins Brittany Mahomes (center) at the Chiefs-Packers game on Dec. 3, 2023. PHOTO: PATRICK MCDERMOTT/GETTY

Taylor Swift was spotted cheering on Travis Kelce on Sunday night.

The “Lavender Haze” singer, 33, watched from a box as the Kansas City Chiefs tight end, 34, and his team faced off against the Green Bay Packers in Green Bay, Wisconsin.

Swift, dressed in a bright red coat, could be seen snapping photos of the field. A fan-shared video on X (formerly Twitter) showed the Grammy winner walking around the box, taking video footage. Swift was joined by Brittany Mahomes, wife of Chiefs quarterback Patrick Mahomes.

Taylor Swift attends the Chiefs-Packers game on Dec. 3, 2023.PATRICK MCDERMOTT/GETTY

Last week, a source told PEOPLE that the couple was the “real deal.”

“They’re still a little shocked by all of it — that he’s dating the Taylor Swift, but they’ve seen how down to earth she is with his friends and family,” the insider close to the Kansas City Chiefs star said exclusively.

The source added that the relationship is “growing” because Travis and the music superstar both have found success in their own worlds — and they continue to appreciate one another’s accomplishments.

“They’re both really hard workers, and he acknowledges her art is hers, and he has what’s his,” the source told PEOPLE. “He understands the territory their relationship comes with and like he said, isn’t letting any of the hoopla impact how they’re growing together.”

The source concluded, “Their relationship is about the two of them, and he sees Taylor for who she is and vice versa.”

Last month, Travis traveled to Buenos Aires, Argentina to watch Taylor perform during her Eras Tour. There, Travis met her dad for the first time. In an episode of the New Heights with Jason and Travis Kelce (Presented by Wave Sports + Entertainment) podcast a few days later, Travis and Jason discussed how things went in South America.

Jason, 36, also called out Travis for leaving Scott, 71, “hanging” when he didn’t return a high-five after Taylor changed the lyrics of “Karma” to give the Chiefs tight end a shoutout.

“Yeah, Mr. Swift, I apologize big guy,” Travis said. “Aw, man. I missed that. I never miss a high-five, too. Big high-five guy. It’s the most electric thing you can do at an event and so — sorry Mr. Swift.”

Of the lyric change, Travis said he “had a little bit of a clue” that there was something coming, but once he “heard it come out of her mouth, [it] still shocked me.”

Travis Kelce, Taylor Swift.JC OLIVERA/GETTY IMAGES; AMY SUSSMAN/GETTY IMAGES

“I was like, ‘Oh, she really just said that.’”

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Recently, both of Travis’ parents revealed that they’ve been converted to Swifties after previously not being avid fans of the megastar.

Last month, Donna Kelce told PEOPLE she would “not” describe herself as a Swiftie as she shared, “My era was Earth, Wind and Fire, Chaka Khan, things like that. That’s more my music.”