BEIJING (AFP) - Alexander Zverev underlined his rich potential as he reached the ATP Finals in London for the first time with his quarter-final victory at the China Open on Friday.

The 20-year-old German joins Rafael Nadal and Roger Federer as confirmed entrants for the end-of-season spectacular and is the youngest player to qualify since Juan Martin del Potro in 2008.

Zverev, the world number four enjoying a breakthrough year, sealed his spot with the best in men's tennis after a straight-forward 6-2, 6-3 victory over Russia's Andrey Rublev in Beijing.

Zverev, who faces another young talent in the unpredictable Australian Nick Kyrgios in Saturday's semi-finals in the Chinese capital, said: "I think it's great for any player to qualify for a prestigious event that we have in London.

"It's really an award for I think every player that shows that, you know, you've been one of the best players, not only for one or two weeks in a year, but you've been one of the best players for the whole year.

"That's something special, that's an amazing achievement for me and I think for all the other guys as well," said Zverev, who is chasing a sixth title this season.

The London Finals begin on November 12 and another five spots are still up for grabs.