Indio, California — 

Coachella day two was heavy on alt-rock throwbacks including a highly anticipated No Doubt reunion, but it was Taylor Swift — who wasn't on the lineup and didn't perform -- creating buzz on Saturday.

Her mere presence at the mammoth festival in the California desert set the internet alight, after she made a much-speculated appearance... as a fan, canoodling and dancing with beau Travis Kelce as Bleachers performed a rollicking set.

The rock band Bleachers is fronted by Jack Antonoff, Swift's friend and longtime producer.

Kelce's blocking skills came in handy as the 6'5" (1.96 meters) NFL tight end did well to obscure his wildly famous girlfriend from view, as the couple enjoyed the show from just offstage.

Still, an AFP journalist saw the lovebirds twirling and singing along during the performance of Antonoff, who's co-written and produced several of Swift's albums.

Fan videos quickly started circulating online. Swift's cameo comes less than a week before her forthcoming album, "The Tortured Poets Department," drops on April 19.

Shortly after the Bleachers set Swift and Kelce were caught by fan cameras as they stood in the VIP section for a blazing performance from Ice Spice, the Bronx rapper who collaborated on a remix of Swift's "Karma."

The crowd went berserk when Ice Spice shouted out her megastar pal — but the rapper performed "Karma" on her own with a backing track, giving Swift the chance to watch a rendition of her own song from the vantage point of the crowd.

The 34-year-old billionaire is currently on break from her blockbuster Eras tour.

Some fans had speculated Swift might join friend and fellow Antonoff associate Lana Del Rey, who headlined Friday's opening night.

There's always next weekend, which is essentially a repeat of the first three days of the festival but usually includes a few shakeups.

Tyler, the Creator was the top-billed act Saturday, bursting onto the stage in flames from inside a camper van that was parked in a set mimicking a desert mountain scene.

The eccentric performer — who sported both Palestinian and Congolese flag pins — invited a number of special guests including Kali Uchis, Childish Gambino and A$AP Rocky.

Doja Cat is on deck to headline Sunday.

Alt-rock roots and Paris Hilton

Coachella started as a rock festival but in recent years it's leaned increasingly into pop, rap and the Latino megastars who rule the streaming charts.

But Saturday's lineup offered a portrait of nostalgia: No Doubt — the group fronted by Gwen Stefani — played together for the first time in 15 years.

Stefani, 54, bounded across the stage boasting the vocals of her youth, leading the crowd in singalongs of the group's classics including "Just A Girl" and "Don't Speak."

English rockers Blur also took the stage, while stoner reggae rock group Sublime — the 1990s act beloved for hits including "Santeria" — drew throngs of fans to the main stage for a sunset performance featuring the late frontman Brad Nowell's son Jakob leading the way.

Vampire Weekend made a last-minute return to the desert, having last performed there more than a decade ago.

The veteran indie rockers whose hits including "Cape Cod Kwassa Kwassa" were brought in just last week, and frontman Ezra Koenig, who sported a striped Pogues sweatshirt, told cheering fans he'd been leaning back sipping ranch water — a cocktail of seltzer, tequila and lime — in Texas when he got a text asking if they'd come on board.

The group just released their fifth album, "Only God Was Above Us," and played a mix of fan favorites and new work, including a 15-minute honky tonk mash-up.

They also randomly brought Paris Hilton onstage to play a quick round of cornhole -- a popular North American bean bag-based lawn game — as part of a giveaway of chocolate for front-row fans.

"I haven't played this game since 'The Simple Life,'" the cowboy-hat wearing socialite and reality TV icon quipped, a referencing to the cult mid-2000s series she starred in with Nicole Richie.

"Make some noise for 'The Simple Life!'" yelled Koenig to laughs and applause.

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