The fourth seed won the biggest title of his career on Sunday, crushing world No.25 Khachanov 6-3 6-1 in one hour and 19 minutes in the gold medal match.

The 24-year-old showed no signs of slowing down against the recent Wimbledon quarter-finalist after pulling off a comeback semi-final win over Djokovic on Friday.

That boilover victory sabotaged the world No.1's plans to become the first man to claim all four grand slams and an Olympic title in the same year.

It also ensured Zverev's countrywoman Steffi Graf remains the only tennis player to win the golden slam - a feat she achieved in 1988.

Now he has joined her as an Olympic champion.

It marked Zverev's 16th - and biggest - tournament victory.

Zverev collapsed to his knees in tears after his win on Sunday, appearing in almost disbelief after surpassing his previous career highlights - a 2018 ATP Finals triumph and his 2020 US Open runner-up finish.

"I can't compare it because this is so much bigger than anything else in sports," he said.

"I've won the World Tour Finals but a gold medal at the Olympics, the value is incredible because you're not only playing for yourself, you're playing for your country.

"There is nothing better than this."

Zverev broke 12th seed Khachanov for the first time to lead 2-1 and always looked in control, winning seven games in a row to take the first set and lead 5-0 in the second before icing the win with his first match point.

For Germany, Zverev's win improves Tommy Haas' 2000 Sydney Games silver medal and matches Graf's 1988 singles success and compatriots Boris Becker and Michael Stich's 1992 doubles gold.

Earlier, French Open champion Barbora Krejcikova teamed up with Katerina Siniakova to add Olympic women's doubles gold to their stellar career haul.

The top seeded Czech pair overpowered Swiss duo Belinda Bencic - the Tokyo singles gold medallist - and Victorija Golubic 7-5 6-1 in 85 minutes.

Krejcikova and Siniakova have now added Olympic gold to their three grand slam titles they have won together.

Their winning run includes victory at this year's French Open where Krejcikova won both the singles and doubles titles.

Their victory on Sunday marked the first tennis gold for their country since Miroslav Mecir won the men's singles final in 1988 for then Czechoslovakia.

The final event on the tennis schedule in Tokyo was the all-Russian mixed doubles decider, with Anastasia Pavlyuchenkova and Andrey Rublev prevailing over Elena Vesnina and Aslan Karatsev 6-3 6-7 (5-7) 13-11.

Australian Associated Press