Nick Kyrgios produced a serve-and-volley masterclass to topple world number one Daniil Medvedev 6-7(2), 6-4, 6-2 for his eighth straight win on a day of upsets, while American Tommy Paul rallied to beat Spanish second seed Carlos Alcaraz.
US Open champion Stephens again ended former world number one Victoria Azarenka's hopes of a fairytale comeback by beating her 3-6, 6-2, 6-1 in an afternoon encounter, while French Open champion Ostapenko beat unseeded American Danielle Collins in the nightcap, staving off a set point en route to a 7-6(1), 6-3 triumph.
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.
'There have been a lot of ups and downs and I feel really happy, I've always kept belief'
Rafael Nadal has broken lots of records in his career but they do not matter to the Spaniard, who on Wednesday strolled into the French Open semi-finals after compatriot Pablo Carreno Busta quit with an injury less than an hour into the match.
Novak Djokovic kicked off his season in style with a 7-5, 7-5 win over Canadian talent Denis Shapovalov on his favourite Rod Laver Arena court on Tuesday before returning to lead Serbia to a doubles victory that sealed their ATP Cup opener 2-1.
Novak Djokovic recovered his poise to win the Rome Masters title and Wilander says Djokovic will use the pain of his US debacle to inflict maximum damage on the Parisian clay.
Novak Djokovic threw his racket on the ground, drawing a warning from the chair umpire.
Canada named rising star and world number 69 Denis Shapovalov in its squad to take on India in the upcoming Davis Cup World Group Play-off tie, scheduled in Edmonton from September 15.
Novak Djokovic's stunning disqualification from the US Open on Sunday for striking a line judge with a ball is the most difficult moment in his career, said his former coach Boris Becker.
The second round match against Argentine Federico Delbonis lacked nothing in quality power tennis but was almost entirely devoid of drama and the most notable incident came late in the third set when the ball flew off top seed Nadal's racket and hit a ballgirl on the head.
Murray, who suffered an elbow injury in March and made his return from a five-week layoff on Wednesday after a first-round bye, won the opening set in 48 minutes before losing concentration.
Djokovic sets sights on Paris Olympics
Novak Djokovic was unexpectedly beaten by fifth-ranked Alexander Zverev, quashing his hopes of winning an Olympic singles gold medal, the only major honour missing from his long list of accolades.
'There was a lot of speculation about whether it was deserved. I accepted it, I moved on.'
Djokovic was disqualified while trailing Spaniard Pablo Carreno Busta 6-5 in the opening set of their fourth-round tie on Sunday, striking a line judge with a petulant swipe of the ball.
Top seeds Leander Paes and Raven Klaasen of South Africa lived up to their billing and entered the semi-finals of the men's doubles event at the ATP Chennai Open with a hard-fought win over Indian pair of Mahesh Bhupathi and Saketh Myneni.
Spain's third seed Roberto Bautista Agut made a smooth entry into the men's quarter-finals at the ATP Chennai Open tennis tournament with a fluent 6-3, 6-2 win over German Peter Gojowczyk.
Serena will not be in the US team for the Tokyo Olympics
Novak Djokovic is aware of Kei Nishikori's battling qualities having lost twice to the Japanese in 17 career meetings.
The 34-year-old practised for an hour on Thursday evening at the Rod Laver Arena and his fitness was improving "little by little, step by step", sources close to Nadal told Reuters.
He leads the men's seedings ahead of defending champ Roger Federer, with Bulgarian Grigor Dimitrov seeded third.
Djokovic withdraws from Western & Southern Open, to 'turn focus on US Open.'
Johnson to meet Medvedev in Winston-Salem final
Images from Day 6 of the French Open matches played at Roland Garros in Paris on Friday.
Reaction to Novak Djokovic's disqualification from the US Open for striking a line judge with a ball during his match against Pablo Carreno Busta on Sunday.
It was Roger Federer's fastest defeat since losing to Franco Squillari in 54 minutes in Sydney in 2003.
Tennis matches at the Ariake Tennis Park will begin from 3pm local time (0600 GMT) from Thursday, governing body International Tennis Federation said after requests from players who had struggled in the stifling weather.
Images from Day 8 of the 2021 French Open at Roland Garros in Paris on Sunday
Women's tennis's biggest names still remaining at the US Open take centre stage on Sunday with Grand Slam winners Maria Sharapova, Venus Williams, Garbine Muguruza and Petra Kvitova all appearing on Arthur Ashe Stadium.
Andy Murray and Emma Raducanu clinched hard-fought wins in their first round matches at Indian Wells.
India's top singles player Somdev Devvarman was on Saturday drawn to a play a qualifier while wild cards Yuki Bhambri and Jeeven Nedunchehziyan will have to fight it out with top-100 players in their first rounds at the Aircel Chennai Open.
Sweden and Novak Djokovic's Serbia took the two best runners-up spots and a place in the last eight by virtue of their better match win-loss records among the second placed sides throughout the group stages.
World number one Rafael Nadal recovered from an upset loss against Belgium's David Goffin to win the deciding doubles match and send Spain into the semi-final of the ATP Cup teams event in Sydney in the early hours of Saturday. Spain will now play host nation Australia in the inaugural event, while Serbia, led by world number two Novak Djokovic, take on Russia.
India were on Tuesday pitted against European powerhouse Spain as their Davis Cup World Group play-off opponents for the home tie as the International Tennis Federation announced the draw in London.
Maria Sharapova's contentious and captivating US Open run came to an end on Sunday when Latvia's Anastasija Sevastova beat her 5-7, 6-4, 6-2 to reach the Flushing Meadows quarter-finals.
The 38-year-old, who has lost six games so far in the tournament, dispatched his hapless opponent in only 62 minutes winning the second-round match 6-0, 6-3.
Jack Sock ended local favourite Julien Benneteau's run at the Paris Masters with a 7-5, 6-2 victory to reach the final and move to the brink of an ATP Finals spot on Saturday.
Top seed Roger Federer needed less than an hour to dispatch Benoit Paire 6-1, 6-3 and reach the quarter-finals of the Swiss Indoors tournament on Thursday -- treating his home fans to another masterclass.
Top seed Nadal extended his winning streak to 13 matches with a 6-2, 6-1 demolition of American Jared Donaldson in the Qi Zhong Stadium before World No 2 Federer, to the delight of his sizeable Chinese fan club, got the better of Argentina's Diego Schwartzman 7-6(4), 6-4.