Las Vegas, Nevada - Taylor Swift treated fans to an extra surprise during her latest stop on The Eras Tour with the arrival of the tour's first special guest!

The 33-year-old played two shows at Allegiant Stadium in Las Vegas on March 24 and 25, where she continued her tradition of playing two surprise songs not included on the permanent setlist.

Luck was in the air on night two, as Swift made things even more exciting with a special guest to help with her performance!

Marcus Mumford, the singer-songwriter best known as the frontman of Mumford & Sons, joined the Anti-Hero artist for an acoustic rendition of cowboy like me.

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The evermore track was made into a duet for the occasion, making it a truly once-in-a-lifetime experience for the crowd.

As it turns out, Mumford has more of a connection to the song than Swifties might have realized!

While introducing him, Swift shared that he graciously offered his home studio when she needed a place to record evermore amid Covid-19 lockdowns, and he even contributed background vocals to the album version of cowboy like me.

Fans couldn't get enough of the first-ever live performance of the song, with many praising Mumford's vocals in the new duet version.

But that wasn't Swift's only big surprise for the second weekend of The Eras Tour!

On her first night in Sin City, the Lavender Haze artist surprised fans with acoustic performances of Our Song and Snow on the Beach.

The studio version of the latter features Lana Del Rey, who unfortunately did not come out as a special guest for the show, but Swift told fans she wanted to pay tribute to the 37-year-old in honor of her new album release.

Fitting with the cowboy theme, Swift also performed White Horse from her second album, Fearless, at the Saturday show in Las Vegas.