Travis Kelce's week-long bachelor party shows no signs of slowing down after the Kansas City Chiefs tight end was spotted at a NASCAR race in Southern California on Sunday afternoon.

Kelce and his pals have been partying for days, with multiple events in LA and beyond - and they finished their big weekend down in San Diego to watch NASCAR's first ever race at Naval Base Coronado.

The NFL star's presence came as a big surprise to viewers when he appeared out of nowhere on the Amazon Prime coverage, acting up for the TV cameras alongside his friends - which appeared to include Taylor's brother Austin.

The boys' trip to downtown San Diego is for an historic event, with NASCAR racing on an active military base for the first time in its 78-year history. 

The picturesque location features an aircraft carrier backdrop and the hospitality boxes - where Kelce and his friends are believed to be positioned for the race - has been built inside maintenance hangars on site.

Kelce's NASCAR adventure comes at the end of a long week of parties and events, which began in LA when he hosted a live episode of his New Heights podcast alongside brother Jason at the Orpheum Theatre on Monday.

On Wednesday, the brothers joined Travis' best friend Ross Travis and Druski for a guys' night out at the ultra-exclusive Bird Streets Club in West Hollywood.

According to Page Six, the group spent several hours together before leaving shortly after midnight, with Kelce and his brother reportedly the last members of the party to depart.

Bird Streets Club has become a popular destination for high-profile figures from the worlds of entertainment, music and sport.

Previous visitors are said to have included Leonardo DiCaprio, Drake, Justin and Hailey Bieber, and members of the Kardashian-Jenner family.

On Friday night, Kelce was out-and-about again, attending Chris Lake's Los Angeles concert with his pals.

The NFL star was seen shooting off a bubble gun into the crowd and bobbing to the music, per TMZ, which posted fan footage of the event.

One fan wrote, 'happy bachelor party, mr swift,' across a video of Kelce pointing the  bubble gun at the crowd amid the tiny bubbles.

Kelce wore a blue plaid shirt and light trousers along with a red baseball cap and tinted shades while enjoying the British DJ and producer's heart-pumping house and tech music.

In another fan video shared on TMZ, Kelce fist-pumped the air and shouted into the mic while a Swift remix was played. The fan captioned it: 'tayhusband: AAAAHHHHHHH.'

On the opposite coast, meanwhile, Swift's Rhode Island compound has been humming with activity.

The singer is said to be hosting a lavish bachelorette-style party for her friends at the oceanfront estate. Swift's high school pal Abigail Anderson has been spotted at the property along with some other lady friends.

Since Wednesday afternoon, security and women dressed in black and white have been spotted on the rooftop balconies of the entertainer's home.

Swift and Kelce's wedding is said to be just weeks away with a huge reception being planned at New York City's Madison Square Garden, which would encompass the reported 1,000 guests they are inviting.

No doubt, famous guests will include Selena Gomez and her new husband Benny Blanco, supermodel Karlie Kloss, Cara Delevingne, Zoe Kravitz, Ed Sheeran, Suki Waterhouse and, one would assume, her significant other Robert Pattinson, and the Haim sisters – Este, Danielle and Alana.

Swift has also extended an olive branch wedding invite to Blake Lively, an insider told the Daily Mail. The two friends had a falling out over Lively’s contentious legal battle with It Ends with Us co-star Justin Baldoni.