Djokovic reached his 12th Wimbledon quarter-final and is looking for a sixth title at the All England Club, and a record-equaling 20th Grand Slam trophy.
Williams needed three sets to get by Mihaela Buzarnescu in the previous round and she clearly did not want to go the distance again this time, beating Collins 6-4, 6-4.
The official night program includes just one match in the main stadium each day; so far Serena Williams, Novak Djokovic and Daniil Medvedev have joined Nadal in being placed in that slot.
Italian Open, Grigor Dimitrov, Alejandro Davidovich Fokina, Roberto Bautista Agut, Tommy Paul, Nadia Podoroska, Serena Williams, Laura Siegemund, Madison Keys, Sloane Stephens
The top-ranked Barty rallied from a big third-set deficit and overcame a match point to win her opening match against qualifier Kristina Kucova, 6-3, 4-6, 7-5.
Qatar Open: Former champions Karolina Pliskova, Petra Kvitova, Victoria Azarenka through to quarters
It was Jabeur who defeated the Czech during their last encounter in Doha in 2020 but this time it was 2017 Qatar champion Pliskova who booked her ticket to her first hard-court quarter-final since 2020 Dubai.
Keys hit 24 winners against 13 for the sixth-seeded Bencic, who was coming off a loss to Iga Swiatek in the final of the Adelaide International on Saturday.
The charters and the early arrivals are all part of Tennis Australia's attempt to have the tournament happen despite a ban on international arrivals into the country.
The 25-year-old American's announcement came just hours after former world number one and three-time major winner Andy Murray said he too had tested positive for the virus.
Now that there is a plan in place for top-level tennis to resume - starting in August in Italy, then Washington, with Grand Slam action to follow in New York, then Paris, assuming the COVID-19 outbreak allows - it's time to consider ways in which the sport will look different.
Australian Open champion Sofia Kenin, US Open winner Bianca Andreescu to be part of 16-player team event in Charleston in June
American Kenin, who won this year’s Australian Open, and Canada’s Andreescu, the 2019 US Open champion, will take part in the Credit One Bank Invitational, which will be aired on the Tennis Channel and begin on 23 June.
Australian Open 2020: Wang Qiang upsets Serena Williams in three sets; Caroline Wozniacki bids adieu in farewell tournament
Williams owns seven trophies from the year's first major championship and this was her earliest defeat there since also bowing out in the third round all the way back in 2006
Australian Open 2020: Roger Federer cruises into third round; Fabio Fognini emerges victorious after marathon five-setter
Checkout all the match results of the men's singles fixtures from the third day of the Australian Open 2020.
Brisbane International: Karolina Pliskova earns hard-fought win over Madison Keys to clinch her third title
A day after clinching a near three-hour semi-finals duel with Naomi Osaka, Pliskova overcame a mid-match blip to triumph 6-4, 4-6, 7-5 in the final at the Pat Rafter Arena.
Brisbane International: Naomi Osaka suffers semi-final loss against Karolina Pliskova; Madison Keys rallies to beat Petra Kvitova
Madison Keys came from a break and set down to beat two-time Wimbledon champion Petra Kvitova in the Brisbane International semifinals on Saturday.
Brisbane International: Naomi Osaka overcomes Kiki Bertens in three-setter to advance into semi-finals
Third seed Naomi Osaka survived another testing three-setter to beat Dutchwoman Kiki Bertens 6-3, 3-6, 6-3 to advance to the semi-finals of the Brisbane International.
Brisbane International: Americans Madison Keys, Alison Riske and Danielle Collins notch up straight-sets victories to make quarter-finals
Eighth seed Keys was pushed in the first set by hometown favourite and former US Open champion Samantha Stosur but eventually prevailed 7-5, 6-3 in 78 minutes
Brisbane International: Naomi Osaka battles through Maria Sakkari's attempted comeback to win opening match
Naomi Osaka defeated Greece's Maria Sakkari 6-2, 6-7 (4), 6-3 on Tuesday to set up a second-round match with American Sofia Kenin.
Kiki Bertens became the first player to qualify for the semi-finals of the WTA Elite Trophy in Zhuhai, China. The tournament is the second-tier year-end competition on WTA Tour.
Tennis Rankings: Coco Gauff makes huge jump of 39 places to No 71 in WTA rankings, Ashleigh Barty retains No 1 spot
Another good performance in Luxembourg this week could see Gauff knocking on the door of the top 50