David Goffin shocked the tennis world when he downed none other than Roger Federer at the ATP World Tour finals on Saturday.

The 26-year-old fought back from a set down to defeat who many consider the GOAT in a thrilling 2-6 6-3 6-4 at London's O2 Arena.

And before claiming his famous victory, Goffin had spoken about the differences between playing Federer and Rafael Nadal. 

He explained: “I played Rafa this year on clay court and on this surface, and it was completely different matches.

“The rebound is higher on clay, it's heavier. It's tough to control the ball on the clay.

“Here it is a little bit easier. There is no bad bounce. You can take the ball earlier. He defends a little bit. He's defending much better on clay. He can slide.

“Against Roger, on his best surface, it's indoor.

“It's this surface, along with the grass. There is no wind. It's tough to play higher, to find the loop when you play here on this kind of surface. It's not easy. It's perfect for Roger.”

With Nadal pulling out and Djokovic and Murray not competing in London the door was wide open for Federer to end a great season by scooping this showcase event.

However, despite reaching the final of this event 5 times in the last 7 years, the 19 times grand slam champions hasn't walked away with the trophy since defeating Tsonga back in 2011.

And although Goffin had never defeated the Swiss in his previous six attempts, it was a case of seventh time lucky.

He had announced beforehand: “But I will try, like I said, to do my best to find some solutions, try to play my game, be aggressive.

“If he's aggressive and he hit the ball really hard with his forehand, he's dangerous.”

Goffin became the first Belgian player to break into the men's top 10 earlier this year and subsequently this is his first taste of competing in the prestigious season ending event, and what an introduction to life with the big boys.

Do you think there's a Grand Slam in Goffin's future? Have your say in the comments section below.