Travis Kelce enjoyed one of the biggest and best days of his NFL career in Kansas City's victory over the LA Chargers on Sunday.

The Chiefs' Super Bowl-winning tight end was on track for a record-breaking game at half time, scoring a touchdown in the 31-17 win.

His touchdown was helped, in no small part, by a solid push from the developing partnership with Taylor — teammate Jawaan, that is.

Yet, for many, the real story — and real Taylor — was in the stands, where pop superstar Taylor Swift was watching on.

It shouldn't be a surprise that Kelce was impressive with Swift watching — he averages 108 yards receiving per game when Swift is watching on in the stands, compared to just 46.5 per game on the occasions she hasn't been present this year or, as the NFL wrote on their in-game graphic, when "left to his own devices" under a "You belong with TE" header.

The Chiefs are still undefeated when Swift attends their games — she's attended four now and only missed one game against the Minnesota Vikings in Minneapolis in Week 5 (although the Chiefs won that one too).

However, it's not just on the field where the Swift Effect has been in evidence.

The numbers back up the hype 

Rumours had been swirling that there was a "friendship" developing between Swift and Kelce for a short while earlier in the season, but she was first seen at the Chiefs' Arrowhead stadium on September 25, sitting next to Travis's mother Donna Kelce in the player box as Kansas City powered past the Chicago Bears.

Kelce even scored a touchdown, with Swift shown screaming "let's f***ing go" in an extravagant show of support, before hugging mumma Kelce.

It had clearly been a topic of conversation in the locker room.

"I heard she [Swift] was in the house," quarterback Patrick Mahomes said after the game.

"I knew I had to get it to Trav … I think he wanted to get in the end zone just as much as all the Swifties wanted him to."

The impact off the pitch was instant.

Hollywood Reporter said Fox's broadcast of the Chief-Bears game averaged 24.32 million viewers, the most of the weekend.

Fans were treated to multiple — and I mean, multiple — shots of Swift in her suite, cheering on her then-rumoured love interest.

The day after the game, sales of Travis Kelce's jersey were up nearly 400 per cent, according to a spokesperson for Fanatics, the NFL official apparel partner.

The spokesperson told AP that Kelce's 87 jersey "was one of the top-five-selling NFL players" on that day.

In fact, according to data analysis of Google Trends by betting site Replay Poker, searches for "Travis Kelce jersey" were 12 times higher than average and the highest since February's Super Bowl.

In that game, during what may become known as the pre-Swift era, Kelce caught six passes for 81 yards and scored a touchdown.

The data also showed that search interest in Kelce's jersey overtook searches for quarterback Patrick Mahomes's kit for the first time in their shared history.

Swift's appearance also resulted in a three-fold increase in ticket sales in a 24-hour window for Chiefs home games on ticket selling website StubHub.

The interest did not stop there.

The following week, the Chiefs were in New York to take on the Jets. 

Speculation that Swift would be there supposedly increased interest among punters in attending that game.

StubHub reportedly saw a 175 per cent increase in sales for the game, with nearly 20 per cent of tickets for the game available on the site sold the night of Swift's appearance, according to Reuters.

The Chiefs-Jets game was also the second-highest-selling game for the weekend.

And Swift did turn up, with an entourage that included Blake Lively, Ryan Reynolds, Sophie Turner, Sabrina Carpenter and Australian actor Hugh Jackman. Talk about star power.

Because Swift is such a massive star that even being associated with the 33-year-old is a recipe for success — in the 24 hours following Swift's appearance at Arrowhead, Kelce had over 300,000 more Instagram followers and his podcast went from being ranked in the low 100s to number one in the Apple Store.

Sure, he's still a long way shy of the 274 million Instagram followers Swift has on the social media platform, but then again, so is the NFL's official account, which has 28.5 million followers — roughly 10 per cent of Swift.

The increase in sales is important, but the demographic is, too.

According to Reuters, digital media player manufacturer Roku said the largest demographic increase for the Chiefs-Bears game was among women aged 18-49.

That represents a 63 per cent increase from the week prior.

The NFL has enjoyed a roughly 50 per cent female audience share for a while and is the number one ranked sport among Americans aged between 8-24, according to its own statistics — but any opportunity to target a new demographic cannot be sniffed at.

Pop culture explosion

The partnership between the NFL and Swift is a twinning of arguably the two biggest forces in American popular culture — and the NFL are doing everything they can to cash in on it.

"It was a perfect storm of pop culture and sports colliding in a really positive way, with two incredibly passionate fan bases merging together and interacting in ways that they hadn't before,' Ian Trombetta, the NFL's senior vice president of social, influencer and content marketing told AP. 

"So for us, it's fantastic,"

"Hopefully those — especially the young women — that have now gained an interest in not only Travis Kelce, but the NFL more broadly, can stay with us throughout the year and years to come."

When the Chiefs won the Jets game, the NFL briefly changed its status to reflect's Swift's presence. 

And that in itself is not a surprise.

Travis Kelce is a generational talent at tight end and the second-best player in the NFL's best team of this generation behind Patrick Mahomes.

He also knows the value of self-promotion.

As well as hosting a podcast with his brother, Jason Kelce, who plays centre for the Philadelphia Eagles, he has also appeared on TV reality shows to boost his brand.

Kelce appeared on the eponymous reality dating show Catching Kelce in 2016, when "50 women from 50 states vie to win the heart of the pro football player". 

As he said of the show when he was guest host of Saturday Night Live following the Chiefs' Super Bowl win: "It was kind of like The Bachelor, except instead of roses, I handed out footballs, and instead of watching, people did not."

In the end, Kelce chose Maya Benberry (Kentucky) and they dated. Briefly. 

Since then, though, Kelce has not been shy about wanting to meet Swift — he even made her a friendship bracelet, being a well-known marker of Swifties — with his number on it and wanted to give it to her after she performed in Kansas City in July earlier this year, but he did not get the chance to meet her.

"I was disappointed … She doesn't meet anybody, or at least she didn't want to meet me, so I took it personal," Kelce said of the non-meeting on his podcast.

He later named Swift as his celebrity crush and, as such, acknowledged that he had "brought all this attention to me".