Taylor Swift shares the glare with boyfriend Travis Kelce, Mahomes on Super Bowl Sunday

Las Vegas: Pop superstar Taylor Swift chugged a drink, bit her nails, buried her face in her hands and hugged her friends throughout a nerve-shredding Super Bowl LVIII.

At the end, it was hugs and kisses for her Kansas City Chiefs tight end boyfriend Travis Kelce on a field smothered with glitter and ticker tape as the world digested an epic, dynasty-creating victory over the San Francisco 49ers.

Swift was central to the Super Bowl story all week but at the conclusion of the 25-22 overtime win she was just another exhausted, ecstatic fan like so many around her, happy to share superstar billing with Chiefs quarterback Patrick Mahomes - for one day at least.

Swift had been performing in Tokyo on Saturday, and when she took her seat at the Allegiant Stadium, it ended a week-long will-she-won't-she saga that had dominated the lead-up to the football event of the year.

Her arrival some two hours before kick-off had fired an almost palpable frisson around the stadium and social media rapidly filled with pictures and video footage of the singer.

The cameras followed her as she walked through the bowels of the stadium with friends Blake Lively and Ice Spice dressed in a black top, black jeans and with a red Chiefs jacket slung over her shoulder.

A punishing travel schedule in which she had flown from Japan to the US for a brief stop before she heads on the long flight down to Australia for seven more sell-out concerts meant her presence had been far from a foregone conclusion.

When giant television screens showed Swift for the first time, a ripple of cheers went around the still-mostly empty stadium.

But while Chiefs fans, neutrals, TV viewers and legions of "Swifties" the world over were delighted by her presence, the overwhelmingly pro-49ers crowd in the stadium was perhaps understandably less enthusiastic.

In the first half when cameras showed Swift up on the big screens, it prompted 49ers jeers. She handled that by quickly grabbing her drink, and chugging it all down before slamming the glass on the surface in front of her.

It was the first of what seemed to be several unguarded moments and as the on-field tension ratcheted up and the game headed into overtime -- Swift nibbled a nail, hugged her friends and hid her face.

"SWIFTIES"

Swift, who last weekend won the Grammy Award for album of the year for a record fourth time, has attended 12 Chiefs games since she began dating Kelce last year, boosting already sky-high NFL ratings.

With her army of devotees known as “Swifties”, the 34-year-old brings megawatts of superstar power to the NFL and the Swift-Kelce love story marks a collision between two of the most powerful forces in American pop culture.

As shirt sales spike and viewership grows, the romance has brought millions of dollars of added brand value to the Chiefs and the NFL, according to research done by Apex Marketing Group.

"Taylor Swift's association with Travis Kelce and appearances at the Chiefs game has generated an equivalent brand value of $331.5 million for the Kansas City Chiefs and the NFL," Apex President Eric Smallwood told Reuters in an email.

NFL Commissioner Roger Goodell could be forgiven for rubbing his hands in glee.

"Having the Taylor Swift effect is a positive," he told reporters this week.

"She knows great entertainment and I think it is great to have her a part of it. Obviously it creates a buzz ... another group of young fans that are interested and saying ‘why is she going to this game?," he said.

"They're - both Travis and Taylor - wonderful people and they seem very happy," he said.

Happy hardly covers the enormous smiles sported by America's golden couple after the latest chapter of their adventure.