Petra Kvitova, who missed part of the 2017 season after a home invasion left her with a badly cut left hand, continues her remarkable comeback when she faces American Venus Williams.
Here are five things to watch for on day eight of the US Open on Monday.
Novak Djokovic had hoped to have the crowd behind him as he began his bid to win the US Open and complete the calendar-year Grand Slam, but the Serb said the atmosphere was "not ideal" as Flushing Meadows fans roared on his underdog opponent.
Federer, Djokovic headline Day 2 at Flushing Meadows
Serena Williams was the runner-up in Flushing Meadows each of the past two years
Images from Day 4 of the 2021 US Open in New York on Thursday.
The 190th-ranked Indian stretched 20-time Grand Slam Champion Roger Federer to four sets in opening round of the US Open.
Belgian Kim Clijsters crowned her remarkable comeback by beating 19-year-old Caroline Wozniacki of Denmark 7-5, 6-3 to win the US Open women's title on Sunday.
Unseeded Kim Clijsters's improbable charge into the US Open semi-finals has surprised the Belgian as much as anyone.
American teenager Melanie Oudin is playing like Cinderella, doing everything she can do prevent the clock from striking midnight.
American teenager Melanie Oudin's spectacular run at the US Open gathered momentum when she beat Russian 13th seed Nadia Petrova 1-6, 7-6, 6-3 to reach the quarter-finals on Monday.
Serena Williams and Ekaterina Makarova sprinted into the semi-finals of the U.S. Open on Wednesday but marathon man Kei Nishikori had to go the distance to upset Stan Wawrinka and become the first Japanese man into the last four of a grand slam in 81 years.
A glance at the scoreboard in the third set pushed Alexander Zverev to raise the level of his play
Novak Djokovic was eliminated from the Grand Slam after inadvertently hitting a ball into a line judge's throat during his fourth round match on the Arthur Ashe Stadium court.
Facing the prospect of empty stands at the first fanless Grand Slam since the coronavirus outbreak, top contenders at this year's US Open admit that the unprecedented new hush will take some getting used to.
Sixth-seeded Briton Andy Murray entered his first Grand Slam final when he upset the world No 1 at the US Open on Sunday.
Novak Djokovic said he overreacted to jokes about his long list of injuries when he lashed out at Andy Roddick after defeating the American on Thursday to reach the semi-finals of the US Open. Roddick had commented to the crowd courtside after his previous match on the assorted maladies cited by Djokovic, who complained about stomach, hip, ankle and breathing problems during his five-set win against Spain's Tommy Robredo.
Rafael Nadal turned dream wrecker at Flushing Meadows when he downed American favourite Mardy Fish 3-6, 6-1, 6-4, 6-2 in a rowdy late late show that closed Wednesday's programme at the US Open.
Spanish teenager Carlos Alcaraz beat Norway's Casper Ruud 6-4, 2-6, 7-6(1), 6-3 in the men's singles final at the US Open on Sunday to win his maiden Grand Slam title and rise to world number one for the first time.
Venus Williams rejected the suggestion she might be content to serve as an inspiration to younger players after her 6-1, 0-6, 7-5 defeat to fellow American Sloane Stephens in the semi-finals.
'I hope that as an association we make the best decision for our business, for our health, for the tournaments, for public.'
It was not expected to happen but Juan Martin del Potro did not care. The Argentine left Roger Federer, and the rest of the tennis world, stunned as he subdued the five-times champion in a pulsating five-set final to claim the US Open crown on Monday.
'But I'm sitting out for the people, for my Aussies, for the hundreds and thousands of Americans that have lost their lives, for all of you. It's my decision.'
Serena Williams and Andy Murray had brief hiccups on the way to convincing victories at the US Open, each choosing different tactics to remain on track for a long ride into the year's final Grand Slam.
Sharapova was granted a wildcard entry to the last Grand Slam of the season but received a tough first-round draw in the shape of Romanian Halep.
Justine Henin maintained her recent grand slam mastery over Serena Williams with a 7-6 6-1 triumph in the quarter-finals of the U.S. Open on Tuesday.
Rafael Nadal advanced to the second round of the US Open but a knee injury could hamper his campaign.
Ana Ivanovic was unceremoniously tossed out of the US Open on Thursday by an obscure Frenchwoman who had never played a tour-level match before arriving at Flushing Meadows. Julie Coin set alight the Arthur Ashe Stadium court when she produced the match of her life to shatter the world number one's title hopes in the second round 6-3, 4-6, 6-3.
IMAGES from all the action on Day 7 of the US Open played at the USTA Billie Jean King Tennis Center at Flushing Meadows in New York on Sunday.
Andre Agassi continued to defy the odds and elude retirement by shocking eighth seed Marcos Baghdatis in a five-set thriller.
Images from Day 9 of the 2021 US Open in New York on Wednesday.
Federer hammered Wang Yeu-tzuoo of Taiwan while second seed Nadal crushed Mark Philippoussis in the first round at the US Open.
'Leylah asking for the mic back to acknowledge 9/11 was one of the classiest, most empathetic, and mature things I've ever seen in a post-game moment ... and she's only 19. I'm blown away'
Roberta Vinci beat her opponent and the rain to storm into the quarter-finals of the US Open on Monday just before a thunderstorm forced play to be suspended.
Serena has remained one title behind Margaret Court's all-time record since bagging her 23rd Grand Slam singles trophy
Naomi Osaka said she had spent a lot of time during the coronavirus shutdown thinking about how she wanted to approach her tennis.
Images from Day 7 of the 2021 US Open in New York on Sunday.
