When Maren Morris told the audience at London's Royal Albert Hall that she had someone special set to join her that evening, she lived up to her words. Niall Horan, whom she dueted with for his "Seeing Blind," surprised the crowd with his guitar and a big smile as the pair harmonized on the 2017 hit.

Horan praised the show on Instagram, calling Morris his "buddie" and raving "What an amazing show!"

Morris herself was sentimental following the set: "Headlining that room has been a goal of mine for so long and last night, it felt like a lucid dream," she wrote on Instagram. "I cried when I got back to the hotel because it’s bittersweet that this tour is done, but holy shit, the memories that have been made with my amazing band, crew, and you guys."

This isn't the only guy who's joined Morris on stage in the U.K. recently. Last Sunday (May 27), the singer brought out her husband, fellow musician Ryan Hurd, in Leeds, much to the delight of the crowd.

The singer will now head back across the pond to come home to the U.S. She'll resume the rest of her U.S. Girl: The World Tour dates, which wrap in November. Her all-female support acts including Cassadee PopeRaeLynnTenille Townes,  Kassi Ashton and Hailey Whitters supporting her on select dates. Morris also has plans to appear at number of summer music festivals.

See Maren Morris and Ryan Hurd's Sweetest Pictures Together