Roger Federer

Djokovic continued his imperious progress through the men's draw, negotiating a potentially tricky encounter with Diego Schwartzman 6-3 6-4 6-4 to reach the last eight at Melbourne Park for the 11th time.

The seven-times champion only added to a strong feeling around the tournament that the Serbian is again the man to beat at the year's first Grand Slam as he ousted the Argentine in just over two hours at Rod Laver Arena.

Federer, chasing a record-extending 21st Grand Slam, came from behind to beat Hungarian Marton Fucsovics 4-6 6-1 6-2 6-2.

The Swiss, 38, beat the Hungarian 4-6 6-1 6-2 6-2 and will play American Tennys Sandgren in the last eight.

After losing the first set, Federer breezed through the second and third, winning seven successive games.

He twice broke Fucsovics in the fourth set before serving out the win on his third match point.

Federer battled for more than four hours to see off John Millman in the third round and he looked unsure of the wind conditions on Rod Laver Arena.

Unlike his main rivals, Federer, who won his last Grand Slam in 2018 at Melbourne Park, opted out of the inaugural ATP Cup to spend more time with his family before launching his 22nd season on Tour.

The third seed's pre-tournament news conference was dominated by questions about the ongoing bushfires in Australia and the role of the top men's players on the air quality issue during the tournament.

"And I'm playing Steve Johnson, by the way, for those who care," a smiling Federer told reporters. "I don't know, I figured that's why I'm in Australia, but that's okay."

A crowd of 42,217 watched an exhibition match between Federer and Zverev at Plaza de Toros Mexico – the world's largest bullring – in Mexico City on Saturday.

Serena Williams and Kim Clijsters had previously set the record in their exhibition contest in 2010, which attracted 35,681 fans in Brussels.

But that figure was topped as 20-time grand slam champion Federer defeated Zverev 3-6 6-4 6-2 in the "The Greatest Match".

Swiss icon Federer earned a brilliant 6-4 6-3 victory at the O2 Arena in London on Thursday to join Dominic Thiem in advancing to the semi-finals at the Serbian's expense.

It was the 19-time grand slam champion's first win against Djokovic – whose defeat meant Rafael Nadal will end 2019 as the world number one – since 2015, with the 32-year-old having been triumphant in each of their previous five encounters.

The most recent of those saw Djokovic stave off a championship point before clinching the Wimbledon title following a tie-break at 12-12 in the fifth set.

Austrian Thiem completed a hat-trick of wins over the 20-time grand slam champion in 2019 with a 7-5 7-5 victory on the opening day in London.

Federer now faces a tough task to advance from Group Bjorn Borg, which also contains Novak Djokovic and Matteo Berrettini.

The 38-year-old committed 30 unenforced errors and won 11 of 22 points on his second serve in an uneven showing at the O2 Arena on Sunday.

"I thought he played well. The start definitely didn't help. That put me on the back foot a little bit," Federer said.

The pair have won 36 grand slams between them and triumphed at the season-ending tournament a collective 11 times, with Federer leading that head-to-head tally by one.

Joining the Swiss maestro and Djokovic in Bjorn Borg Group will be Dominic Thiem and Matteo Berrettini.

The Springboks thrashed favourites England 32-12 in Yokohama on Saturday and tennis superstar Federer sent a video message praising their achievement.

Federer's mother, Lynette, was born in South Africa and the 20-time grand slam champion clearly enjoyed the nation's success in Japan.

"Siya, it's Roger here. Couldn't be more happy for you and the team," he said in a video shared on the Springboks' Twitter account on Sunday.

"What a victory, what an amazing team effort. You guys spent so much time together and you ended up with the big win.

The Swiss will be aiming to secure a third medal next year in Tokyo; he struck gold playing alongside Stan Wawrinka in the men's doubles in Beijing in 2008, then collected silver in the singles tournament four years later in London, falling in the final to home favourite Andy Murray.

Federer, 38, also represented his country at the Olympics in 2000, losing out in the bronze-medal match to Arnaud Di Pasquale, and 2004, but missed Rio 2016 while recovering from a knee injury.

Djokovic, the defending champion won 7-6, 2-6, 7-6, 1-6, 13-12 on Sunday (Monday morning NZ time).

It was an epic encounter between two of the greatest tennis players of all-times.

The scene was set for a cliffhanger with a tiebreaker in the first set, won 7-6 by Djokovic.

Federer, 37, fought back imperiously to take the second set, 6-2.

But Djokovic, 32, prevailed 7-6 in the third after another tiebreaker.

Federer broke the Serb's serve in the fourth to win 6-4 and take the tussle to a fifth set decider.