Roger Federer is optimistic his back is on the mend as he prepares to return to action in the Wimbledon warm-up event on Stuttgart's grass courts this week.
Djokovic's challenger will be a 22-year-old who is bidding to become the first Greek to win a singles major.
The seven-time major champion, speaking as part of a tour to promote his new book 'But Seriously', said that while he has great respect for Serena, he would place the 23-time Grand Slam winner "like 700 in the world" on the men's circuit.
Roger Federer handed Nick Kyrgios a 6-4 6-1 7-5 tennis masterclass by storming into the fourth round of the U.S. Open on Saturday with a ruthless display that left the Australian talking to himself and waving the white flag.
The World No 4, recovering from a knee surgery, eyes January return for Hopman Cup, Aus Open
Sticking to a limited schedule has helped Roger Federer enjoy a renaissance late in his career but the Swiss says rest time is now over and he is looking forward to returning to action at the Mercedes Cup in Stuttgart.
The Indo-French pair was staring down the barrel, trailing by two sets but put the match on even keel before eventually going down 2-6, 4-6, 7-6(5), 6-4, 9-11 in three hours and 37 minutes on court number six.
Novak Djokovic believes he is the best player in the modern era
Federer dismisses Nadal's suggestion to play ATP Finals on clay
Federer cannot fathom how his perfect tennis can be defeated again and again by the fury of Nadal. That's why he was crying. And it hurts Nadal. But he will carry on beating him because he cannot help himself.
A month shy of his 35th birthday, Roger Federer knows time is not on his side if he wants to triumph at Wimbledon again, but he is adamant his goals stretched beyond the world's most famous Centre Court.
Wildcard Harriet Dart was probably surprised, therefore, when she looked up to see the Duchess of Cambridge sat in the front row of seats on Court 14 on Tuesday.
Nadal becomes just the fourth man to achieve 1,000 singles victories in the Open Era, behind Jimmy Connors (1,274), Roger Federer (1,242) and Ivan Lendl (1,068).
Having let three match points slide in the fourth set against Roger Federer on Centre Court, Marin Cilic may be forgiven for wanting to rewind the video and replay the key moments again. His Swiss conqueror snatched a pulsating fourth-set tiebreak 11-9 before winning 6-7(4) 4-6 6-3 7-6(9) 6-3 to reach his 11th Wimbledon semi-final and keep up the tilt for an eighth title.
The 35-year-old Swiss, showing no sign of losing his edge, improved to 19-1 this year, winning the Australian Open in five sets over Nadal, and BNP Paribas Open in straight sets over fellow Swiss Stan Wawrinka.
Rewarding as it was for Rafael Nadal to become the only player to win the same Grand Slam 12 times by chalking up his dozen at last month's French Open, the Spaniard arrived at Wimbledon this year like a man on a mission. In the end, however, it became mission impossible as he lost to inspired Roger Federer in Friday's blockbuster semi-final.
Marin Cilic handed Roger Federer "a tennis lesson" in the semi-finals of the U.S. Open on Saturday, his coach Goran Ivanisevic said.
After Sunday's thrashing Medvedev was left wondering if his best would have made any difference.
Marin Cilic, thrashed by Roger Federer in straight sets in Sunday's Wimbledon final, said he had been suffering from a blister in his foot during the showpiece clash.
Tennis great Serena Williams limped out of Wimbledon in tears on Tuesday after her latest bid for a record-equalling 24th Grand Slam singles crown ended in injury.
Defending champion Roger Federer will meet big-serving Canadian Milos Raonic in the final of the Brisbane International after the Swiss top seed dismantled rising Austrian talent Dominic Thiem 6-1, 6-4 in Brisbane.
Former world number one Roger Federer has pulled out of this week's Madrid Open with a back injury.
Roger Federer bounced back to form with a quick-fire win over Mikhail Kukushkin of Kazakhstan on Tuesday as he began his bid for a seventh title at his hometown tournament in Basel.
Murky skies and drizzle could not dampen the enthusiasm of spectators arriving on Monday
The US Open is the biggest tournament in America's tennis calendar. Enough reason for the big personalities from Hollywood, former tennis champions and other celebrities to catch their favourite tennis stars in action.
Earlier in July, it was announced that Murray and Kim are expecting their second baby.
Former world number one Andy Murray is in line to play Grigor Dimitrov in the opening round of the inaugural ATP Cup, with Bulgaria qualifying among the final six teams in the nation-based tournament.
Despite being the king of Wimbledon, Federer has found himself in the same strict bubble as every other player in the draw this year, rather than in his usual plush rented house with his family a stroll away from the grounds.
Speculation is rife that all is not well in among compatriots Roger Federer and Stanislas Wawrinka.
Andy Murray may have been the forgotten man at the US Open but gave the crowd and Stefanos Tsitsipas a match to remember, forcing the third seed to grind out a 2-6, 7-6(7), 3-6, 6-3, 6-4 win on Monday and avoid the opening round shocker.
Only once in 16 previous appearances has Federer not survived the group stage, back in 2008. IMAGES from the ATP Finals played at The O2 Arena in London on Sunday
- 'It's probably been the best preparation I've ever had for Wimbledon because we have a week more on the grass' - 'This year I feel my game is better'
Tennis players need to respect ball boys and ball girls, Roger Federer said in the wake of a row following Fernando Verdasco's rant over a sweaty towel.
Serbian tennis superstar Novak Djokovic has said that he thinks former World No.1 Roger Federer, who he faces on Tuesday at the ATP World Tour Finals, is noticeably slower on court.
Roger Federer was given a fright before reaching the semi-final of the inaugural Istanbul Open.
Nadal said his back was still bothering him against world number 56 Djere
The world number one was virtually guaranteed a semi-final berth before walking on court at the O2 Arena, but made doubly sure by cruising past Tomas Berdych in little more than an hour.
Kevin Anderson took down Novak Djokovic for a second straight night as Team World rallied to win the final two matches and reel Team Europe's lead back to 7-5 after the second day of the Laver Cup in Chicago.
Top seed Roger Federer dispatched Greek third seed Stefanos Tsitsipas 6-4, 6-4 in the semi-finals of the Swiss Indoors championships in Basel.
Immigration Minister Alex Hawke's office said he was still considering whether to use his discretionary power to cancel Novak Djokovic's visa.