Alex de Minaur’s US Open preparations hit a significant hurdle as the world No.8 crashed out in the second round of the Cincinnati Open against world No.73 Reilly Opelka.

De Minaur was unbeaten in the pair’s five previous encounters, but the 211cm American, who is the tallest player on the ATP Tour, overpowered the Australian time round, claiming a straight sets victory 7-6 (8-6), 6-4 in one hour and 41 minutes.

Opelka sent down 14 thunderous aces and cracked 38 winners, while also holding his nerve to save all seven break points he faced throughout the match.

Watch the biggest Aussie sports & the best from overseas LIVE on Kayo Sports | New to Kayo? Join now and get your first month for just $1.

“I didn’t serve as well as I’d have liked to, but everything else was working,” Opelka said.

“I was pretty consistent from the baseline the whole match. My serve fluctuated and it was a bit of a surprise that the other things came through well for me today. I think I returned really well too.”

The loss came out of the blue for de Minaur as he entered the clash with a Tour-best 24 hard court wins this season, including having won his 10th career title in Washington last month.

Alex De Minaur of Australia reacts after getting broken by Ben Shelton of the USA during their quarterfinal match at the National Bank Open in Toronto, Tuesday, Aug. 5, 2025. (Frank Gunn/The Canadian Press via AP)Source: AP

He also reached the quarter-finals at the Canadian Open last week, losing to eventual champion Ben Shelton.

The loss to Opelka was de Minaur’s first match in Cincinnati as the sixth seed was handed a first round bye.

After a heavy schedule, some added time to refresh before the US Open may be a blessing in disguise for de Minaur.

Although, he is now susceptible to his ranking slipping and therefore missing out on a crucial top eight seed that would guarantee avoiding the likes of Jannik Sinner and Carlos Alcaraz until at least the quarter-finals at Flushing Meadows.

TORONTO, ONTARIO – AUGUST 05: Alex De Minaur of Australia walks back to his corner while playing Ben Shelton of United States during the National Bank Open Presented by Rogers at Sobeys Stadium on August 05, 2025 in Toronto, Ontario. (Photo by Matthew Stockman/Getty Images)Source: Getty Images

It was a far better outing for Australians Alexei Popyrin and Adam Walton.

Popyrin, the 21st seed, defeated Spaniard Martin Landaluce 7-6 (7-3), 6-3 after like de Minaur, being afforded a first round bye after making the quarter-finals in Toronto, where he was beaten by Alexander Zverev in three sets.

Popyrin will next face ninth seed Andrey Rublev.

TORONTO, ONTARIO – AUGUST 04: Alexei Popyrin of Australia celebrates while playing Alexander Zverev of Germany during the National Bank Open Presented by Rogers at Sobeys Stadium on August 04, 2025 in Toronto, Ontario. Matthew Stockman/Getty Images/AFP (Photo by MATTHEW STOCKMAN / GETTY IMAGES NORTH AMERICA / Getty Images via AFP)Source: AFP

World No. 85 Walton pulled off a giant-killing effort, downing out of sorts 12th seed Daniil Medvedev 6-7 (7-0), 6-4, 6-1.

The victory against the Russian came in the pair’s first meeting.

Former world No.1 Medvedev cracked more aces (18 to 5) and winners (41 to 27), but the Australian crucially made less errors (29 unforced errors to 32 as well as two double faults to seven).

Walton also seized the key moments better, converting four of six break points, while only conceding one break.

Awaiting in the next round is 22nd seed Jiri Lehecka.

TORONTO, ONTARIO – JULY 29: Adam Walton of Australia celebrates while playing Alexander Zverev of Germany during the National Bank Open Presented by Rogers at Sobeys Stadium on July 29, 2025 in Toronto, Ontario. Matthew Stockman/Getty Images/AFP (Photo by MATTHEW STOCKMAN / GETTY IMAGES NORTH AMERICA / Getty Images via AFP)Source: AFP

It was a disappointing day for Australia’s women with 15th seed Daria Kasatkina, Kimberly Birrell and Ajla Tomljanovic all suffering losses.

Kastkina went down to Italian Lucia Bronzetti in a topsy turvy contest 6-3, 1-6, 6-4.

Birrell meanwhile was beaten by fourth seed Jessica Pegula 6-4, 6-3 and Tomljanovic fell to Danish 16th seed Clara Tauson 6-3, 6-7 (7-5), 6-4.

Teenager Maya Joint was the only Australian female to progress to the Round of 32 after she upset Brazilian 18th seed Beatriz Haddid Maia 6-4, 4-6, 6-5 yesterday, and 12th seed Ekaterina Alexandrova awaits in the next round.

MONTREAL, CANADA – JULY 30: Maya Joint of Australia plays a backhand against McCartney Kessler of the United States during their second round match on Day Four of the WTA 1000 National Bank Open at IGA Stadium on July 30, 2025 in Montreal, Quebec, Canada. Minas Panagiotakis/Getty Images/AFP (Photo by Minas Panagiotakis / GETTY IMAGES NORTH AMERICA / Getty Images via AFP)Source: AFP