Here are eight women to watch during the US Open which starts on Monday.
Top-ranked defending champion Osaka, a 21-year-old from Japan, defeated Serena Williams in last year's US Open final but dubbed the experience "bittersweet" after Williams received a game penalty in a dispute with the umpire and Osaka was booed during the match and award ceremony.
Osaka went on the win this year's Australian Open title, becoming the first player since Williams in 2015 to win back-to-back Slam singles crowns.
During a topsy-turvy 2019 season, she has won the Australian Open but then slumped out early at the next two majors.
A third-round exit at the French Open was followed by the first-round demise at Wimbledon.
Second-ranked Barty, a 23-year-old Australian, captured her first Grand Slam title at this year's French Open.
She became the first Australian to lift the trophy at Roland Garros since Margaret Court in 1973.
Barty won two other titles this year, taking the Miami hardcourt crown and Birmingham trophy on the grass.
She made a fourth-round exit at Wimbledon last month after having become only the second Aussie world number one after Evonne Goolagong Cawley.
The Australian has enjoyed a breakthrough season in which she won a maiden slam at the French Open and also briefly climbed to the top of the world rankings.
She has had mixed results since triumphing at Roland Garros but remains a top threat.
US tennis great Serena Williams posted an Instagram video featuring a young African-American girl overcome by emotion as she addressed a public meeting, finally able to force out the words: "We are black people, and we shouldn't have to feel like this."
The 24-year-old American won last week's WTA Cincinnati title, jumping eight spots to 10th in the world rankings, three shies of her career-high and back in the top 10 for the first time since June 2018.
Keys defeated Slam winners Garbine Muguruza, Venus Williams, Svetlana Kuznetsova, and Halep on the way to the Cincy crown.
She reached her only Grand Slam singles final at the 2017 US Open, losing to Sloane Stephens, and last year lost a US Open semi-final to eventual champion Osaka.
The American and her powerful forehand seem to be best suited for the US Open, where she reached the final in 2017 and the semi-final a year ago.
Having won the Western & Southern Open in the run-up to the year`s final slam, she will enter the tournament in top form.
The 27-year-old Romanian defeated Serena Williams in last month's Wimbledon final, dominating the 23-time Grand Slam singles champion after having dropped nine of their 10 prior meetings.
It was the second Grand Slam title for Halep, who won the 2018 French Open.
Her best US Open result came in a 2015 semi-final run. She arrives in New York ranked fourth in the world.
After destroying Serena Williams in the Wimbledon final, the Romanian proved that she has what it takes to succeed on grass as well as clay, on which she won her first Grand Slam title at the French Open in 2018.
The former world number one will be hoping to carry that confidence into the US Open, where her last two appearances have ended in first-round defeats.
It has surprisingly been a barren year for Svitolina who capped off 2018 by winning the WTA Finals, which was her fourth title of the year.
Since capturing her first WTA title in 2012, Svitolina has won at least one trophy every season.
But so far in 2019, she has failed to reach a final.
However, a semi-final run at Wimbledon would have given her a much-needed boost and she will be looking to build on that in New York.
The 15-year-old took the tennis world by storm when, as a qualifier ranked 313 in the world, she beat five-times champion Venus Williams in the first round of Wimbledon.
Her heroics did not stop there as she also saved two match points against Polona Hercog to reach the last 16.
That sensational run earned her a main draw wildcard at Flushing Meadows, where she will be eager to show off her credentials as a future great.