Watch: GUNS N' ROSES Joined By CARRIE UNDERWOOD At London Concert

GUNS N' ROSES was joined by country-pop superstar Carrie Underwood on stage during the band's concert Friday night (July 1) at London, England's Tottenham Hotspur Stadium.

Underwood made a surprise appearance toward the end of GUNS N' ROSES' main set, performing "Sweet Child O' Mine" with Axl Rose and his bandmates. She later returned to the stage during the encore to sing "Paradise City".

This past April, Rose joined Underwood on stage at the Stagecoach country music festival in Indio, California to perform the same two songs. At the time, Carrie called the collaboration "the greatest night of my life."

Back in 2015, Underwood told E! in an interview with she really wanted to sing with Rose at some point in her life. She said: "I've covered enough GUNS N' ROSES stuff, and it was people like him who taught me how to sing."

"I look at people like him and Freddie Mercury, those people who were doing all these crazy runs. It was so different," Underwood added.

In 2013, Underwood delivered a faithful cover of "Paradise City" at the CMA Music Festival in Nashville.

Two years ago, while promoting her book "Find Your Path: Honor Your Body, Fuel Your Soul, And Get Strong With The Fit 52 Life", Underwood appeared on an episode of "The Tonight Show With Jimmy Fallon" and talked about flying to Las Vegas to see her favorite band GUNS N' ROSES and called it "one of the best nights" of her life.

"We were nowhere near Las Vegas, so naturally I said, 'Let's go to Las Vegas with the band and go see GN'R play,'" Underwood shared with Fallon. "It's kind of a life-long dream of mine I never thought would happen. Couldn't waste that opportunity, so I abandoned my husband, abandoned my children, went to Vegas, and saw GUNS N' ROSES. Amazing."

She continued: "Usually, when I go to concerts, I'm like, in a box on the side, which is great — it has its perks, there's usually a bathroom in there, it's kind of awesome,' she explained. "But you miss the energy of the crowd. Because we were in Vegas, we were just in there with everyone else, it was absolutely incredible. You could feel everybody, everybody was screamin', I was screamin' — I was, like, 'I'm never gonna see none of these people ever again, I'm gonna act like a fool!. It was amazing."

Following that show, Underwood actually met Rose backstage. "It's hard to meet your heroes, because I do consider him someone who taught me how to sing," she said. "But he was super cool and great and nice and we talked. We're best friends."

Carrie said in a 2014 interview that late QUEEN frontman Freddie Mercury was high on her list of first loves.

"I've always been a huge fan and lover of Freddie Mercury," she said. "I would listen to him when I was a kid. He could do so many amazing things with his voice. People like that — who had incredible voices — I was always drawn to. I would want to try to do what they do. They were my teachers."

She also said that if you scrolled through her iPod, you’d find some really hard rock music, like MUDVAYNE.

"When I work out, I like to listen to things that are really angry," she said. "I couldn't do it on a daily basis or driving in my car. I think that would be kind of weird."