Wimbledon champion Barbora Krejcikova knocked out in the second round of the US Open; Maya Join; Ajla Tomjlanovic; Rinky Hijikata

Wimbledon champion Barbora Krejcikova was knocked out of the US Open as Australia was brought back down to earth after a hugely successful opening two days.

The No.8-seeded Krejcikova went down in the second round, defeated by qualifier Elena-Gabriela Ruse 6-4, 7-5.

Krejcikova won her second grand slam singles title at the All England Club earlier this year, but then she didn’t play any matches after the Paris Olympics. She acknowledged last week not knowing where her level of play was.

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Turns out, it wasn’t good enough.

“I mean, winning Wimbledon is amazing. It’s a great, great, great result, I’m very proud about it and how I was able to handle everything there,” said Krejcikova, who hadn’t played a tournament on hard courts since February.

“I think I was playing quite well, definitely better than in the first match. I think my game was improving, but it just wasn’t enough.”

Elena-Gabriela Ruse of Romania celebrates. Getty

Ruse got much more work on the US Open’s hard courts while playing her way into the main draw through the qualifying tournament and was better than Krejcikova on the points that mattered most, fighting back from a 5-3 deficit in the second set to win the final four games.

“Barbora, she’s such a good player, she’s won so many matches in the last two years and it’s just a dream for me,” said Ruse, a 26-year-old from Romania.

No woman has won Wimbledon and the US Open in the same year since Serena Williams in 2012.

Ruse advanced to the third round of a grand slam for the first time and will play No.26 seed Paula Badosa, who eliminated American Taylor Townsend 6-3, 7-5.

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It was a tough day for the Aussies after a successful opening couple of days but they ended day three without winning a set.

Two Australian women were sent packing as Madison Keys rolled past Maya Joint 6-4, 6-0, while Elise Mertens knocked out Ajla Tomljanovic 6-3, 6-2.

Maya Joint of Australia & Madison Keys of the United States shake hands at the net. Getty

“I’m definitely really happy with how I played that match,” Keys said.

“I feel like she [Joint] came out playing really well, and it took a little time to get used to her ball, but once I figured some things out, I was really happy with how I kept the momentum going.”

No.9 seed Grigor Dimitrov swept past Aussie Rinky Hijikata in straight sets as Australia’s hopes now lay with Popyrin on day three.

Fellow Australians, No.10 seed Alex de Minaur, Thanasi Kokkinakis, Jordan Thompson, Chris O’Connell, wildcard Tristan Schoolkate and Max Purcell will play their second-round matches on Friday (AEST).