Selemon Barega took the first athletics gold of the Tokyo 2020 Olympics on a day when Novak Djokovic saw his Golden Slam hopes ended.

Barega topped the podium for Ethiopia as he saw off competition from Ugandan duo Joshua Cheptegei and Jacob Kiplimo on Friday.

The 21-year-old ran a smart race and had the stronger finish in him to see off pre-race favourite Cheptegei, who took silver ahead of compatriot Kiplimo.

"It means a lot to me because I have been practising a lot, not only by myself but together with the Ethiopian people," said Barega, who quickly sets his sights on future success.

"As an athlete the primary target for us is to participate in the Olympics, be a champion, and also be able to break the record.

"So I'm really thinking about future opportunities for me to achieve that, and if possible I'm also communicating with my manager about that."

There was no such joy for Djokovic as his bid to become the first man to win a calendar Golden Slam was crushed by a semi-final defeat to Alexander Zverev.

Djokovic was a set and a break up but the Serbian contrived to lose eight games in a row en route to a 1-6 6-3 6-1 loss.

Germany's Zverev had sympathy for his beaten opponent, who he declared as the greatest of all time.

He said: "I know that he was chasing history, chasing the Golden Slam and chasing the Olympics, but in these kind of moments me and Novak are very close. Of course I'm happy that I've won, but at the end of the day I know how Novak feels.

"I feel sorry for Novak, but he's won 20 grand slams, 550 Masters Series or whatever, you can't have everything.

"He's the greatest player of all time, he will win the most grand slams out of anybody on tour, but I'm also happy that I'm in the final."

Defeat in the mixed doubles means the 20-time grand slam champion will face two bronze medal matches in Japan.

MIXED RELAY WOES FOR USA

The 4x400 metre relay mixed event made its debut in the Olympics on Friday but it did not go well for the favourites as the United States suffered disqualification.

One of the team's baton exchanges was deemed to have taken place outside the designated zone, ending their campaign and leaving the gold medal up for grabs.

Poland qualified fastest with a time of three minutes 10.44 seconds, with the Netherlands close behind and Jamaica also in the mix.

SCHAUFFELE LEADS THE WAY IN RAIN-AFFECTED MEN'S GOLF

Xander Schauffele fired a 63 to move top of the leaderboard at Tokyo 2020, while home favourite Hideki Matsuyama and Rory McIlroy made big moves on Friday.

The threat of serious weather caused another delay on day two, and eventually brought an early end to play with Matsuyama among those not to finish his round.

But Schauffele, who has a big following in Japan as his mother was brought up in the country, sat pretty at 11 under as the stellar names bared their teeth at Kasumigaseki Country Club.

Matsuyama was six under through 16 holes of his second round and eight under overall for the tournament.

McIlroy matched Matsuyama's round-one score but shot five under in round two and is well in the mix four shots back.

A LONG TIME COMING

Ma Long took gold in the table tennis as he became the first man to win consecutive Olympics titles in the event.

It was an all-Chinese final and Ma roared to victory against Fan Zhendong.

China also secured a one-two in the badminton mixed doubles.

IGLESIAS CAN BE CUBA'S HERO

Cuban welterweight fighter Roniel Iglesias earned a third Olympic medal after sinking American Delante Johnson with a sweep of the scorecards.

After a bronze in Beijing and gold at London in 2012, Iglesias savoured another chance to target the top step of the podium.

The 32-year-old said: "It is my third medal which is very important but what I really want is to win the gold medal. It is a historic moment for me and for my country, Cuba. I am very happy at this achievement."

Light heavyweight Ben Whittaker admitted he was a blubbering mess after securing at least a bronze medal for Great Britain. He set up a semi-final against Imam Khataev – representing the Russian Olympic Committee – after scoring a majority points win over Brazilian Keno Machado.

Whittaker was overwhelmed by the result and burst into tears at the realisation he would be taking home a medal.

"That was the hard part, getting that medal," Whittaker said. "I won't relax, but I've pushed through that first door now and all I have to do is start changing that colour. Bronze is a lovely colour but everyone wants gold."

DRAMA APLENTY IN WOMEN'S FOOTBALL

The quarter-finals of the women's football competition delivered on drama in a big way.

Penalty shoot-outs were needed for Canada and the United States to progress to a last-four showdown, with Brazil and the Netherlands their respective victims.

Australia won a seven-goal thriller 4-3 against Great Britain after extra time and will now meet Sweden, who knocked out hosts Japan 3-1.