'90s kids, Federer take '90s knowledge test

Seven ATP Finalists took a quiz on 1990s pop culture, and, to be honest, none of them nailed it. This makes sense, though, as three-quarters of the active field was born in the '90s, and thus couldn't really experience its culture firsthand.

Dominic Thiem, to his credit, could name the stars of Titanic, even though he was four years old when it came out.

(All via Giphy)

Then David Goffin, who was three when Friends premiered, knew the name of the show's coffee shop. ("Easy one, yes!")

And Roger Federer knew how many consecutive times Pete Sampras finished the year at No. 1, because of course he did.

But the hardest question was: What was the Backstreet Boys' first U.K. No. 1 single?

"I know all their songs ... I'm sure I know it," Dimitrov said, despite not knowing the answer. "There's no way I don't know it."

"It's not 'Backstreet's Back,' because that means they were already there," Federer said logically. "I don't think it's 'I Want It That Way.'"

Alas, he had overthought it. "I Want It That Way" was correct.