Top seed and home hope Ashleigh Barty's Australian Open came to a juddering halt in the quarter-finals on Wednesday, just as fans were cleared to return after a five-day coronavirus lockdown. Barty had raised expectations of ending Australia's 43-year wait for a home winner but her campaign was ended by Czech surprise package Karolina Muchova, who stunned the top seed 1-6, 6-3, 6-2. Muchova will face Jennifer Brady in the last four after the 22nd seed beat her fellow American and close friend Jessica Pegula 4-6, 6-2, 6-1. As Victoria state's six million people prepared to emerge from the snap lockdown, tickets went on sale for Thursday – heralding the end of an odd hiatus where matches were played in empty stadiums with fake crowd noises broadcast on TV. Barty's campaign, however, ended in front of 15,000 vacant seats at Rod Laver Arena in a stunning upset by Czech 25th seed Muchova, who came from behind to reach her first Grand Slam semi-final. In hot conditions, Muchova looked on her way out after Barty raced through the opening set, but after a medical timeout she returned to dominate as the Aussie crumbled. "I was a bit lost on the court and my head was spinning so I took a break," said Muchova, while Barty, a semi-finalist last year, called her latest near-miss "heartbreaking". But Barty added: "Will it deter me, will it ruin the fact we've had a really successful start to our season? Absolutely not." After Barty's departure, Brady also staged a comeback to beat Pegula, whose father is the billionaire owner of the Buffalo Bills NFL franchise, 4-6, 6-2, 6-1. Brady's achievement is notable, as she is the last woman standing among those who served a hard 14-day quarantine after arriving in Australia – unlike other players, who were allowed out of their hotels for five hours a day to train. "I felt the pressure from her. She's such an aggressive player," said Brady, who also reached the semis at last year's US Open. "I was looking to push her back and get more on offense. I think I played a really good third set."