Serena Williams of the US reacts during her third round match against Australia's Ajla Tomljanovic (Photo: Reuters/Shannon Stapleton)

The US Open began as a farewell party for Serena Williams and ended with proof of her legacy for Black athletes, USTA player development head Martin Blackman told Reuters.

Williams earned her first Grand Slam title in 1999 at the US Open and took her final bow at Flushing Meadows after announcing she would be "evolving away" from the sport sometime following the year's final major.

Frances Tiafoe carried Williams' legacy into the second week when the latter was unable to add to her 23 Grand Slam titles, going out in the third round.

Read: Williams gives it her all before bidding tennis farewell at US Open

'Big Foe,' as he is known, became the first Black American man to reach the US Open semi-finals after Arthur Ashe in 1972, losing to eventual champion Carlos Alcaraz, and the USTA player development head said this year's tournament would be regarded as an "inflection point".

"This Open, a lot of it has been about connecting the dots," said Blackman, adding, "There's certain inflection points: '99 was one of them, '75 when Arthur won Wimbledon was one of them ... We're going to look back on this one as one of them as well."

Tiafoe was the first man in the US who reached the semi-finals at New York after Andy Roddick in 2006, and he prided himself in the impact he was having on the sport.

"At the end of the day I love that because of Frances Tiafoe there are a lot of people of color playing tennis," Tiafoe told reporters. "That's obviously a goal for me."

This year, a record 776,120 fans watched the main draw at the US Open, with hopes of a champion for American women resting on 18-year-old Coco Gauff, who reached her second Grand Slam quarter-final.

Gauff told reporters she earned her first paycheck when she was performing as a "young version" of Williams in a Television commercial at the age of 9 or 10.

"Sometimes being a woman, a Black woman in the world, you kind of settle for less," said Gauff, adding, "(Williams) never settled for less."

Blackman said that watching Tiafoe and Gauff's performance this year "speaks to the progress that has been made" and the impact of Serena and Venus Williams.

"They've attracted thousands or millions of girls of color into the sport," he said, adding that pioneers like Arthur Ashe and Althea Gibson should not be forgotten.

"But there wouldn't be a Serena and Venus if it weren't for Arthur. There wouldn't be an Arthur if it weren't for Althea."

Read: Tennis superstar Serena Williams to compete in US Open in September