As far as Madureira is concerned, Liverpool lifted it directly from Porto: The teams played in the Champions League’s round of 16 this season, and Madureira said he believed Liverpool’s fans took the song up spontaneously in the stadium. The reality, though, is a little more convoluted.

A few weeks after Porto played Dortmund in 2016, Phil Howard, a Liverpool fan from Wavertree, watched the video of the Super Dragons in the subway station. He had been in Dortmund for Liverpool’s game there, and was searching for clips on YouTube, “trying to see if I was in any of the videos.”

Disappearing down a YouTube rabbit hole, he came upon the Porto video. “I wanted to do a version of it straightaway,” he said. “As stupid as it sounds, I didn’t want Manchester United or Chelsea to get hold of it.”

Howard texted a friend, Liam Malone, to alert him to the song. “I told him this could be the next ‘Ring of Fire,’ ” he said, referring to the Johnny Cash song that provided the soundtrack to Liverpool’s 2005 Champions League win.

It took the two of them some time to come up with acceptable lyrics: It was not for 18 months, till December 2017, that Malone had a flash of inspiration. For the next few weeks, he and Howard tried to spread the word and popularize their creation: They were both at the game in Porto — three months later — where groups of Liverpool fans started singing it on the concourses and in the stands.

Jamie Webster, an electrician and acoustic guitarist, was there, too. “I’d heard murmurs of it at Anfield before,” he said. “But in Porto there was a group of lads singing it. People did not know the words, but they were trying to follow them.” He saw the potential in the chant, too. He found the song online, deciphered the lyrics, and started setting it to music. “I wanted to get it out there,” he said.