Mardy Fish quit in the third set because of a back injury, allowing Andre Agassi to advance to the second round.
Maria Sharapova battled to a 6-4, 1-6, 6-2 victory over in-form Russian compatriot Svetlana Kuznetsova to reach the second round of the Cincinnati Masters on Tuesday.
The gap between the leading four, which also contains Rafa Nadal and Andy Murray, and the chasing pack was again evident as Djokovic beat Argentine Juan Martin del Potro 6-3, 6-2 before Federer saw off fellow-Swiss Stanislas Wawrinka 7-6, 6-3.
It was an emotional win for Aryna Sabalenka, who missed Wimbledon last month due to a shoulder injury.
Rafa Nadal urged tournament organisers to make more consistent surfaces for hard court events after easing past American Taylor Dent 6-2, 7-5 to make the third round of the Cincinnati Masters on Wednesday.
Mahesh Bhupathi and Max Mirnyi advanced to the men's doubles quarter-finals of the Cincinnati Masters after getting a walk over. Fourth seeds Bhupathi and Mirnyi were scheduled to play against Americans John Isner and Sam Querry, who withdrew from the contest due an ankle injury to Isner.
The Indo-Czech duo advanced after fifth seeds Paul Hanley and Kevin Ullyet withdrew while trailing 3-5 in the first set.
Britain's Andy Murray, who lost his Cincinnati Masters quarter-final to American Mardy Fish Friday, was disappointed that tournament organisers had given him three consecutive starts in the midday heat.
Mahesh Bhupathi and Jamie Murray fell to top seeds Mike and Bob Bryan in the second round.
France's Gael Monfils and Gilles Simon suffered early exits from the Cincinnati Masters on Tuesday.
World number one Rafa Nadal battled back to defeat Frenchman Julien Benneteau 5-7, 7-6, 6-2 at the Cincinnati Masters on Thursday and Britain's Andy Murray needed a final set tiebreak to beat Latvia's Ernests Gulbis.
World number one Roger Federer warmed up for the defence of his U.S. Open title in perfect fashion as he beat fourth seed Novak Djokovic 6-1, 7-5 to win the Cincinnati Masters on Sunday.
The Indo-Czech pair were defeated 6-7, 6-7 by second seeds Daniel Nestor and Zimonjic in the quarter-finals of the Cincinnati Masters.
Roger Federer survived a scratchy performance to beat Marcos Baghdatis 7-6, 7-5 to reach the quarter-finals.
Britain's Cameron Norrie stunned world number one Carlos Alcaraz to reach the third round of the Paris Masters.
World No 1 Rafa Nadal fell to Cyprus's Marco Baghdatis 6-4, 4-6, 6-4 in the quarter-finals of the Cincinnati Masters Friday as three of the top four seeds lost out.
Mahesh Bhupathi and Mark Knowles' six-match winning streak ended with their semi-final loss at the ATP Cincinnati Masters event at the hands of Wimbledon champions Daniel Nestor and Nenad Zimonjic. The fourth-seed Indo-Bahamian pair lost 4-6, 3-6 to the second seeded Canadian-Serbian combination in a little over an hour match of the US$3 million hard court event.
Novak Djokovic beat Rafael Nadal 6-1, 7-5 on Saturday to reach the final of the Cincinnati Masters and bring the Spaniard's 32-match unbeaten streak to a halt. Serb Djokovic will meet Andy Murray in the final after the 21-year-old Briton overcame giant Croatian Ivo Karlovic in the day's other semi-final.
World number 19 Moya battled past Argentine Juan Martin Del Potro 7-5 3-6 7-5 in their third-round match, while Hewitt, ranked 20, eased to a 6-3 6-3 win over Austrian Juergen Melzer.
The world's top four players will face off at the Cincinnati Masters on Saturday as Roger Federer, Andy Murray, Rafa Nadal and Novak Djokovic go head-to-head in two mouth watering semi-finals.
Former world number one Ana Ivanovic showed flashes of the form that took her to the pinnacle of tennis as she upset ninth seed Victoria Azarenka 2-6, 7-6, 6-2 in the first round of the Cincinnati Masters on Monday.
Former world number one Marat Safin was dumped out in the first round of the Cincinnati Masters on Monday, beaten 6-3 7-6 by German Nicolas Kiefer.
Ashleigh Barty stunningly lost her chance to regain the number one world ranking when the Australian was beaten in straight sets by Russian Svetlana Kuznetsova.
Novak Djokovic, who claimed his fourth US Open and last major title in 2023, said he has "earned the right" to pick his schedule.'
Elena Rybakina powered into her first Cincinnati Open semi-final after stunning defending champion Aryna Sabalenka 6-1, 6-4 on Friday, while five-times Grand Slam champion Carlos Alcaraz recovered from a second-set blip to beat Andrey Rublev.
Top seed Ash Barty rallied from a set down to power into the semi-finals of the Cincinnati Masters on Friday.
Novak Djokovic overcame a battling Marin Cilic 6-4, 3-6, 6-3 to reach his sixth Cincinnati Masters final on Saturday while Roger Federer enjoyed a less-taxing route to the title match after his semi-final opponent David Goffin retired with a shoulder injury.
Rohan Bopanna and Edouard Roger-Vasselin knocked out Leander Paes and Radek Stepanek to advance to the semi-finals of the ATP Cincinnati Masters.
World No 55 Haase improved to a 2-2 career record against Zverev, including victories in their last two meetings.
Novak Djokovic's bid to add a 100th singles title to his trophy cabinet on Sunday was dashed after he was beaten 7-6(4), 6-3 by world number one Jannik Sinner in the Shanghai Masters final on Sunday.
Novak Djokovic wore down Lucas Pouille after an even first set, dispatching the Frenchman 7-6(2), 6-1 in a Cincinnati Masters quarter-final in Ohio on Friday.
Third seed Alexander Zverev produced a near-flawless display to outclass former champion Holger Rune 6-3 7-6(4) on Saturday and return to the Paris Masters final after a gap of four years.
Jannik and Carlos are the favourites at Flushing Meadows, but don't write these men off!
The bonus amount, a 177% increase on the previous season's payout, will be distributed to players based on performance at the nine ATP 1000 tournaments, which rank just below the four Grand Slams in prestige.
Nadal, who got a first-round bye, defeated Richard Gasquet 6-3, 6-4 to advance.
Nick Kyrgios has been fined $113,000 by the ATP for arguing with the chair umpire and smashing two rackets during his second-round loss at the Cincinnati Masters.
The seventh-seeded Bulgarian advanced to his eighth ATP World Tour Masters 1000 quarter-final with a 6-3, 7-5 victory over Del Potro, who struggled with the intense heat in the closing stages of the one hour, 39 minute match.
Sinner, who was also serenaded with "Happy Birthday" by the crowd, was grateful and slightly bemused by the gift.
A double fault earned the Russian his eighth ATP title after two hours and seven minutes.
Iga Swiatek, Aryna Sabalenka and Coco Gauff, are a handful of contenders ready to swoop in
