Novak Djokovic's hopes of winning a 'Golden Slam' are over after he lost to Alexander Zverev in the Olympic tennis semi-finals.

But German Zverev, 24, came from a set down to win 1-6 6-3 6-1 at the Ariake Tennis Park in Tokyo.

The fourth seed will meet Russian Karen Khachanov in Sunday's final.

World number 25 and 12th seed Khachanov beat Spain's Pablo Carreno Busta 6-3 6-3 earlier on Friday.

Djokovic, 34, will face Carreno Busta in the bronze medal match on Saturday. His previous best at the Olympics is bronze at Beijing 2008.

In March Djokovic set the all-time record for weeks at number one and this month tied Roger Federer and Rafael Nadal for a record 20 Grand Slam titles with his sixth Wimbledon crown.

He has also won the Australian and French Open this year.

Steffi Graf is the only player to win all four Grand Slams and the Olympic title in the same year, in 1988.

Djokovic did not lose a set in his first four games in Tokyo and breezed through the opening set of the semi-final in 37 minutes before going a break up in the second.

But Zverev won 10 games in a row to win the second set and take a commanding lead in the third, with Djokovic looking powerless to prevent the world number five wrapping it up with three breaks in the decider.

Zverev upset Djokovic to win the ATP Finals in London in 2018 and has only reached one Grand Slam final, losing to Dominic Thiem at last year's US Open.