Cincinnati,  England's Emma Raducanu collected a memorable win in the opening round of the Western & Southern Open, defeating Serena Williams 6-4, 6-0 in the pair's first ever meeting.

In what could end up being the second-last tournament of Williams' career, after confirming she will retire after the U.S. Open beginning later this month, the 40-year-old showed fight early on against the 19-year-old world number 11 on Tuesday, reports DPA.

After getting broken to love in the very first game of the match, Williams found her footing, and even secured a break of her own in the opening set, but a second for Raducanu saw her comfortably serve out the opening frame.

The second set was domination, as Williams was only able to win 35 per cent (seven-of-20) of her service points, and 20 per cent (three-of-15) while returning.

Venus Williams, 42, was also eliminated in her opening match, going down 7-5, 6-1 against Karolina Pliskova, with Pliskova now scheduled to take on Elise Mertens in the second round after a 6-1, 6-1 thrashing of Ukraine's Anhelina Kalinina.

Earlier in the day, Olympic gold medalist Belinda Bencic was upset 6-2, 6-7 (3-7), 6-4 by Belgium's Sorana Cirstea, and four-time grand slam champion Naomi Osaka went down to China's Shuai Zhang 6-4, 7-5.

Russian qualifier Anna Kalinskaya collected a top-30 win against Martina Trevisan 7-6 (7-2), 7-5, earning a second-round matchup against world number seven Aryna Sabalenka.

In an all-American clash, the in-form Shelby Rogers was too good for Sofia Kenin, winning 6-2, 6-1 to relegate Kenin to her ninth consecutive loss.

World number two Anett Kontaveit came from a set down to defeat Tereza Martincova 3-6, 7-5, 6-4, while rising star Coco Gauff was forced to retire due to injury while trailing 5-7, 0-1 against Marie Bouzkova.

Simona Halep, ranked sixth in the world, had her hands full in a 6-4, 3-6, 6-3 win against late entrant Anastasia Potapova, and the woman Halep beat in last week's Canadian Open final, Beatriz Haddad Maia, suffered an early exit at the hands of Jelena Ostapenko 6-4, 6-4.

In the late matches, Madison Keys was too strong for Kazakhstan's Yulia Putintseva 7-5, 6-3, and France's Caroline Garcia continued her scintillating form with a big upset 7-6 (7-2), 6-7 (6-8), 6-1 victory against world number three Maria Sakkari, giving her nine wins from her past 10 matches, including over world number one Iga Swiatek last month.