Djokovic has not reached the last eight of a tournament since last year's Wimbledon and has struggled with a long-term elbow injury.
Suspected food poisoning forced Nick Kyrgios to pull out of his much anticipated quarter-finals showdown with Roger Federer at the BNP Paribas Open in Indian Wells.
The match ended in 52 minutes as Williams played her forehand into the net.
Sixth seed semi-finalist Janko Tipsarevic advanced into the last eight of the Chennai Open with a comfortable 6-2, 7-6 (3) win over Russian Alexandre Kudryavtsev on Thursday.
Andy Murray has lost the world number two spot to Roger Federer in the latest ATP rankings released on Monday, after his defeat to Novak Djokovic in the Madrid Masters final.
Lleyton Hewitt proved he is not quite ready to hand over the baton in Australian men's tennis as he used all his years of grasscourt know-how to beat 21-year-old Japanese Kei Nishikori in four sets on Tuesday.
World number one Novak Djokovic has enjoyed a whirlwind trip to Sunday's U.S. Open final, but the top-seeded Serb expects hard work ahead when he meets Stan Wawrinka at Arthur Ashe Stadium. Defending champion Djokovic, who became the third man to hold all four grand slam singles titles at once after his triumph at Roland Garros in June, owns a 19-4 career head-to-head advantage over the Swiss third seed.
Making an impressive start at the ATP Malaysian Open, Indian teen Yuki Bhambri demolished fellow wild card Yew-ming SI of Malaysia 6-2, 6-0 in the first round in Kuala Lumpur on Monday.
Photos from matches played Day 7 of the Australian Open at Melbourne Park on Sunday
Rafael Nadal has pulled out of next week's ATP Tour Finals in London due to injury, so Novak Djokovic will end the year as world number one having returned to the top of the rankings on Monday.
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.
Andy Murray is itching for a break after an exhausting few months, the world number two said, after defending champions Britain were knocked out by Argentina 3-2 in the Davis Cup semi-final.
"I don't know what can happen in the future or not. But yeah, 11 here already is something really unbelievable. I always say the same. It looks, for the most of you, and even for me, looks so difficult to increase that number for anyone in the future. But if I did it, and I consider myself a normal person, probably someone else is gonna do it."
India's Leander Paes and Rohan Bopanna crashed out of the Japan Open following a straight set defeat against Ivan Dodig and Marcelo Melo, in Tokyo on Thursday.
World number one Novak Djokovic is on a French Open semi-final collision course with nine-times champion Rafael Nadal after the draw was made on Friday.
Top seed Rafa Nadal, who has won the tournament 10 times, also reached the last eight after dispatching compatriot Guillermo Garcia-Lopez 6-1, 6-3 and claiming a record-extending 40th consecutive set on clay.
PHOTOS from the Wimbledon Championships matches played at the All England Lawn Tennis and Croquet Club, London, on Saturday
The Spaniard's main rival, Roger Federer, picked the Stefan Edberg Sportsmanship prize for a record fifth successive year.
Frenchman Julien Benneteau caused a stir during an interview on French radio station RMC Sport on Sunday in which he said tournament referees were often kinder to Federer when it came to scheduling his matches.
Rafael Nadal looked like he had never been away as he made a welcome return to Wimbledon with a ruthless 6-2, 6-4, 6-4 win over Japanese wildcard Kei Nishikori on Tuesday.
Rafael Nadal looked like he had never been away as he made a welcome return to Wimbledon with a ruthless 6-2, 6-4, 6-4 win over Japanese wildcard Kei Nishikori on Tuesday.
Second seed Garbine Muguruza, bidding to add the Wimbledon crown to her French Open title, was sensationally beaten in the second round on Thursday by Slovakian qualifier Jana Cepelova 6-3, 6-2 in the shock of the tournament so far.
Swiss teenager Belinda Bencic capped a brilliant run to the Rogers Cup title on Sunday.
Zeeshan Ali, the captain and coach of the men's team, has no clue about Paes's arrival three days before the start of the competition on Sunday.
Serena Williams will try to take a step closer to history on Saturday when she plays her third-round match at the US Open.
Despite the world number nine's withdrawal, a strong field is expected for the event, including Roger Federer, Kei Nishikori, Milos Raonic, Grigor Dimitrov and Juan Martin del Potro, who have all confirmed their participation.
Marin Cilic handed Roger Federer "a tennis lesson" in the semi-finals of the U.S. Open on Saturday, his coach Goran Ivanisevic said.
IMAGES from the matches played on Day 2 of the Wimbledon Lawn Tennis Championships at All England Lawn Tennis and Croquet Club on Tuesday.
List of US Open men's singles champions since the Open Era began in 1968:
Novak Djokovic was given a scare in his North American hardcourt season opener but managed to prevail with a 7-5, 7-6(3) victory over Luxembourg's Gilles Mueller on Wednesday to reach the third round of the Rogers Cup.
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.
Three-times champion and world number one Novak Djokovic has been drawn in a group with U.S. Open champion Marin Cilic in next week's season-ending ATP World Tour Finals in London.
Seven-time Italian Open winner Rafael Nadal lost 7-6(7), 6-2 to Stanislas Wawrinka.
Six-time Australian Open champion Djokovic pulled out of a tournament in Abu Dhabi last week because of continuing problems with his right elbow and wore a sleeve over the joint during his round robin match against the Austrian.
India's most successful One-Day International captain Mahendra Singh Dhoni has beaten football superstars Cristiano Ronaldo and Lionel Messi to secure ninth place in the list of the world's 'most marketable athletes', compiled by the London School of Marketing.
Roger Federer began his latest quest for a 100th ATP title with a battling 6-4, 3-6, 6-1 win over Philipp Kohlschreiber in the first round of the Dubai Duty Free Tennis Championships on Monday.
Andy Murray remains committed to playing a full part in Great Britain's Davis Cup defence despite the prospect of a packed schedule hampering the world number two's chances of leading the side to a repeat triumph.
Nadal, who got a first-round bye, defeated Richard Gasquet 6-3, 6-4 to advance.
A day after celebrating his 36th birthday, Federer played the aggressive game that has propelled him to five titles, including two grand slams, this year, attacking the net and rocketing second serves.