ATP Cup, the new world tennis team event, will feature 24 nations split into six groups across Sydney, Brisbane and Perth.
Rafael Nadal's latest coronation, his 19th Grand Slam title, reinforced the fact the slower courts of the US Open and his obliging knees have turned New York into a land of opportunity.
Novak Djokovic received treatment before the start of the third set against Stan Wawrinka but soon threw in the towel, the 6th time he has retired at a Grand Slam tournament.
World No.1 Novak Djokovic was trailing 4-6, 5-7, 1-2 when he quit, having received treatment on his troublesome left shoulder before the start.
Novak Djokovic was captured on video having a talk with a fan during his pre-match practice session.
Novak Djokovic will meet Stan Wawrinka, the man who beat him in the US Open final three years ago, for a place in the last eight.
Novak Djokovic was treated for a sore left shoulder throughout his 6-4, 7-6 (7/3), 6-1 victory over Argentina's 56th-ranked Juan Ignacio Londero.
Novak Djokovic takes inspiration from talk he could pass Roger Federer for the all-time record total of men's Grand Slam singles titles.
Former world number one Roger Federer, seeking a 21st Grand Slam crown, is seeded third for the tournament.
Daniil Medvedev lifted a first Masters 1000 trophy after settling for runner-up finishes to Nick Kyrgios in Washington and Rafael Nadal in Montreal.
Novak Djokovic wilted under pressure from Daniil Medvedev, falling 6-3, 3-6, 3-6 to the ninth-seeded Russian in the Cincinnati Masters semi-finals.
Ashleigh Barty, the Australian top seed, engineered her second comeback in as many days, overhauling Maria Sakkari 5-7, 6-2, 6-0.
Novak Djokovic was never in danger in his 6-3, 6-4 triumph over 53rd-ranked Spaniard Pablo Carreno Busta.
World number one Novak Djokovic got his US Open build up off to a smooth start with a straight-sets win in Cincinnati.
Rafael Nadal secured his 35th Masters crown, pulling clear by two in that category from Novak Djokovic, who has won 33 of the elite tournaments.
Controversy has arisen over the past months concerning various issues, with ATP Council president Novak Djokovic often on the opposite side of discussions from Rafael Nadal and Roger Federer.
Novak Djokovic's withdrawal means Rafael Nadal will be the top seed in Montreal when main draw begins on August 5.
Novak Djokovic leaned down and plucked a few strands of grass out of the court before popping them in his mouth.