Sharapova's quarter-final defeat by Williams at the 2016 Australian Open was the last competitive match the Russian played for 15 months after she received a doping ban while American Williams was on a maternity break for most of 2017.
Three-time US Open champion Djokovic, who comes into the tournament having won his fifth Wimbledon title, is followed in the seedings by 2017 winner Rafael Nadal.
Organisers are confident a rain-hit opening day will not hold up the tournament.
'I think when I first started, you could win a lot of easy matches, then you're in the quarter-finals, that's when it starts to get a little more tough. Now, like, there's no easy match. Everyone's playing great. Everyone's just doing a lot better'
Badosa beats Fernandez; Swiatek, Halep storm into quarter-finals
The 26-year-old first reached the top last October but lost the spot 16 weeks later having not hoisted a Grand Slam trophy.
'I was aggressive. I had this in my mind, and I wanted to finish the points quicker, but was not that easy with her. She's moving very well. She was returning every single ball'
Simona Halep trailed by a set and 5-1 against Elina Svitolina but somehow dug herself out of a hole before storming to victory to set up a semi-final against Karolina Pliskova.
Serena Williams, hoping to win a record-equalling 24th Grand Slam singles title, will start her campaign against fellow American Kristie Ahn.
Factbox on Japan's Naomi Osaka, who beat Victoria Azarenka of Belarus 1-6, 6-3, 6-3 to win the US Open title on Saturday.
Awesome images from the world of Sport 2018.
As the fans head toward Flushing Meadows, tennis stars gear up with ground-breaking styles to rule the courts.
With no standout favourite in the women's field, it could provide an ideal stage for American Serena Williams to finally end her quest for an elusive 24th Grand Slam title.
Romanian fifth seed Simona Halep advanced to the third round of the U.S. Open with a 6-3 6-4 win over Lucie Safarova on Thursday in the first full match played under a closed roof at Arthur Ashe Stadium. The $150 million retractable roof was installed ahead of this year's tournament and guaranteed there would be at least some action on a muggy and overcast Day Four at the year's final grand slam.
Time is running out for Serena to reach the career milestone that has become one of the sport's longest running storylines.
Images from the French Open women's semi-final matches played at Roland Garros on Thursday
Red-hot Rafael Nadal faces Delbonis, says majors tally not a focus
Serena Williams creates ripples with her latest outfit.
Former champion Stan Wawrinka battled past Russian fourth seed Daniil Medvedev in five sets to reach the Australian Open quarter-finals with a 6-2, 2-6, 4-6, 7-6(2), 6-2 victory. Fifth seed Dominic Thiem kept his flawless record against Gael Monfils intact with a trouble-free 6-2, 6-4, 6-4 victory on Monday to reach his maiden Australian Open quarter-final.
As far as Halep was concerned, her 6-1, 6-3 semi-final win over Elina Svitolina meant that her mother Tania will finally get to experience something she has been dreaming of for more than a decade.
World Number one Simona Halep and Japan's Naomi Osaka are among the players nominated for the Women's Tennis Association (WTA) Player of the Year award.
Swiatek's last defeat on clay came in the WTA 1000 event in Madrid against Australian Barty, who elected not to defend her 2019 French Open title last year due to the COVID-19 pandemic.
Images from the women's singles quarter-finals at Wimbledon on Tuesday.
"I think she will win a Grand Slam. Which one and when I don't know, but definitely clay is a good surface for her."
A summary of Wednesday's action at the US Open.
Unlike the United States and European countries, which are battling to contain the virus, Australia has not had a case of community transmission for 11 straight days and residents have regained most of their pre-COVID freedoms.
Her coach Patrick Mouratoglou believes she is now ready to matching Margaret Court's all-time record of 24 Grand Slams.
Modric beats Djokovic to win Balkan athlete of year
Roger Federer's proposal to merge the tours gets thumbs up from top players.
Serbian Jankovic was serving for the title at 5-4 in the second set but World No 3 Halep won the next three games and battled back for the biggest title of her career.
Serena Williams and Naomi Osaka will join Rafael Nadal and Novak Djokovic in playing a pre-Australian Open warm-up exhibition
Defending champion Serena Williams finished her last US Open tune-up in style by beating Romanian third seed Simona Halep 6-3, 7-6(5) to win the Western & Southern Open on Sunday.
Third seed Simona Halep broke her hoodoo against Belgian Yanina Wickmayer with a 6-4, 6-2 win to sail into the quarter-finals of the Australian Open on Sunday.
Of the top 15 on Forbes' list of best-paid female athletes, 12 were tennis players. Indian badminton player PV Sindhu came in tied for 13th ($5.5 million), with Thai golfer Ariya Jutanugarn ($5.3 million) rounding out the top 15.
It was Novak Djokovic's first match this year after his Australian Open hopes were dashed when he was deported following an 11-day saga revolving around his decision not to have a COVID-19 vaccination.
'I think what Venus and her sister have given our sport is absolutely tremendous. The way they've elevated women's tennis is truly inspiring'
Tactical change helps Halep to French Open semis
However, the 30-year-old Russia belied her own self-doubt with an impressive three-set win over the Romanian to thrust the former world number one back into the spotlight as the toast of the Big Apple.
Halep has struggled for form and fitness since her first-round defeat at the US Open last August and came to Australia on a five-match losing streak and without a coach after long-serving Darren Cahill left for "family reasons".
Romania's Italian Open winner Simona Halep, Spain's Garbine Muguruza and US Open semi-final foe Victoria Azarenka of Belarus present a major challenge for Serena Williams at the upcoming French Open.