He’s the biggest pop star ever to perform during the interval of the Eurovision Song Contest.

But tonight, in the latest episode of The Graham Norton Show, former N’SYNC boy bander Justin Timberlake reveals that he had no clue what the show was when approached to perform.

The 35-year-old admits to Graham that he did not know a thing about the pan-European singing contest “before I said yes to it.”

“Then, when I told people I was doing it they would respond with, ‘Oh, why are you doing that show?’ — “I thought, ‘Why not, a lot of people watch it!’ It was a lot of fun.”

And it also helped his single nudge up the charts all around Europe.

As we previously reported, the “Can’t Stop This Feeling” hitmaker saw his catchy ditty top the charts in 18 countries over the summer — and 12 of them are countries that participated in Eurovision, including Belgium, the Czech Republic, France, Germany, Israel, Slovenia, Sweden and Switzerland.

He’s also had plenty of success at home, where an excited, if relatively small, audience of Americans tuned into the contest for the first time on LOGO TV.

On June 6 the former N’Sync member reached No. 1 on Billboard’s Adult Pop Songs radio airplay chart in the United States.

He managed to do that just five weeks after the song’s release, which tied him for the fastest ascent to No. 1 alongside Adele’s “Hello”, which did so back in November.

Justin is clearly a convert to Eurovision.

In June he traveled to Australia, where he appeared on the Nova 96.9 radio station in Sydney and was full of kind words for Australia’s contestant Dami Im.

He told radio hosts Fitzy and Wippa: “Australia was represented beautifully…I thought that it was a great song and and an amazing performance.”

And guess what? JT wants the contest to go global and to build bridges to America.

“In my opinion there should also be a Worldvision to let everybody in on the fun.”