MASON, Ohio -- Emma Raducanu outlasted Serena Williams in a highly anticipated opening-round match Tuesday at the Western & Southern Open.

Raducanu was dominant from the start, breaking Williams in the opening game before rolling to a 6-4, 6-0 win.

The 40-year-old Williams, who announced she is stepping away from tennis after the US Open, was competing in only her fourth match of the season. The 23-time major champion won her first match in over a year last week at the National Bank Open, defeating Nuria Parrizas Diaz in straight sets before bowing out to Olympic champion Belinda Bencic. 

On Tuesday, Williams struggled to find her rhythm. Raducanu, 19, played clean tennis throughout the match. Raducanu fired just one unforced error to go with eight winners in the first set, while Williams misfired on 12 unforced errors to go with 11 winners. Raducanu broke Williams twice in the opening set to build a quick 4-1 lead before Williams generated her first and only break point of the match. Williams converted to close the gap but Raducanu coolly served out the opening set after 39 minutes.

"I think from the beginning to the end, I maybe looked calm, but I just knew how important every single point was, because you let up a little bit and she's going to be all over you," Raducanu told reporters. "She's just such a legend."

With a set in hand, the Brit raced away in the second set to collect her 12th win of the season, hitting zero unforced errors to close the match. She will face former No.1 Victoria Azarenka in the second round. 

"I think we all need to just honor Serena and her amazing career," Raducanu told the crowd after the match. "I'm so grateful for the experience of being able to play her and for our careers to cross over. Everything that she's achieved is so inspirational and it was a true honor to share the court with her."

Stat of the match: Raducanu hit just one unforced error in the match while striking 14 winners. Williams finished with 19 winners, including seven aces, along with 19 unforced errors.

Raducanu readies for Azarenka: "I remember more recently when she was playing in the US Open and made the final in 2020 during the bubble, I was studying for my exams," Raducanu said. "I hadn't played tennis in like two, three months, and I was kind of just dreaming that one day I'm going to play on Ashe, and one day I'm going to be at that level and playing these great players myself. Everything felt so far away."

Raducanu relishing the win: "I think it's important to really cherish the wins, because I think that if anything, this year has taught me that the wins don't come by easily. No matter what win that is, it means a lot to any athlete, and I definitely am going to take it in, be really proud of myself.

"But it is a fast turnover tomorrow, and I probably have got 12 hours until I'm back on site. I'm playing another Slam champion tomorrow, so it's obviously going to be really difficult. Just going to try to prepare as best as possible."