Two branches of rock music collided when Queen came face to face with the Sex Pistols in 1977.

The groups were at very different stages in their respective careers. Queen was already rock royalty with multi-platinum album sales and hits such as "Killer Queen," "Somebody to Love" and "Bohemian Rhapsody." Meanwhile, the Sex Pistols were the rambunctious upstarts, poster boys for punk, which was then the hottest new fad in rock.

In December of 1976, Queen pulled out of a television appearance on the London-area magazine show Tonight. The Sex Pistols replaced them, resulting in one of the most infamous interviews in television history.

READ MORE: Revisiting Sex Pistols' Anarchy on the TV

So perhaps it was fate that brought both acts to Wessex Sound Studios at the same time in the late summer of ‘77. The groups were working in separate studios, but that didn’t stop Freddie Mercury and Sid Vicious from sparking a brief rivalry.

Johnny Rotten Crawled Up to Freddie Mercury

Queen was busy working on what would become News of the World when their initial uninvited guest stopped by. Their first Sex Pistols visitor was not Vicious, but rather John Lydon, aka Johnny Rotten. According to Queen roadie Peter Hince, the frontman "crawled on all fours across our studio up to the side of the piano, said, 'Hello Freddie,' and left on all fours."

READ MORE: Why Queen Scaled Things Back on 'News of the World'

Bill Price, the engineer who was working with the Sex Pistols on their debut album at the time, knew this probably wasn't a smart move.

"Johnny came back and said, 'I've been to see Freddie,'" Price recalled in the BBC cocumentary series Classic Albums. "And as he said it, there was a tap on the door, Queen's producer said, 'Freddie was playing piano. One of the band members just crawled on all fours across our studio up to the side of the piano, said, 'Hello Freddie,' and left on all fours. Could you make sure he doesn't do it again?'"

Despite the strange behavior, Lydon had at least been polite. Indeed, Brian May later recalled the Sex Pistols singer "was always very respectful" when they crossed paths. Vicious, on the other hand, was not.

Freddie Mercury Put Sid Vicious in His Place

"One day we were in the control room and Fred was sat at the desk," Hince recalled. "And suddenly we heard this voice, and it was Sid Vicious who had come in, and he was clearly the worse for wear. And he called into the room, 'Have you succeeded in bringing ballet to the masses yet?'"

Vicious' question was a reference to a then-recent NME interview in which Mercury had expressed his love of ballet. The Queen frontman was unamused by the bassist's quip.

Watch Freddie Mercury Discuss His Incident With Sid Vicious

"Oh, yes, Simon Ferocious," Mercury responded. "We're trying our best, dear." He then reportedly began flicking the safety pins on Vicious' jacket and commenting on the punk's look. When the bassist stepped towards Mercury, the singer reportedly declared, "What are you gonna do about it?"

"Fred went up, took him by the lapels and pushed him out the door," Hince remembered.

"[Vicious] hated the fact that I could even speak like that," Mercury recalled in an interview following the incident (available above). "I think we survived that test."

"Sid came in. Sid was a moron, you know. He was an idiot," Roger Taylor gleefully added decades later.

Of course, that didn't stop the Sex Pistols bassist from running his mouth. A couple of months after the incident, Vicious gave an interview to BBC Radio One. "I saw Freddie Mercury in the flesh," the rocker declared. "Pictures can't convey how revolting that bloke is. He's absolutely hideous. He's like an old Turk. He's got a great big blue shadow that comes right up to under his eyes. And this disgusting voice. And he warbles away about, 'Oh, the ballet is all good this season.' He's absolutely awful. I've never met anyone like him."

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Gallery Credit: Eduardo Rivadavia