Six months ago, Garbine Muguruza could only play tennis sitting down.
At the Australian Open this week, she is ready to stand up like never before.
Muguruza, 20, is one of the last dozen women in the championship and is the only unseeded player in a half of the draw that includes the defending champion Victoria Azarenka, third seed Maria Sharapova, her fourth-round opponent and fifth seed Agnieszka Radwanska and eighth seed Jelena Jankovic.
But Muguruza, who is ranked 38th in the world, arrives at this high point of her career with two seeded players already among her victims, with her first tournament win fresh in her mind and with the opposition watching her more closely than ever.
The Venezuelan-born Muguruza came into the Open off a victory in the Hobart International earlier this month.
That win didn't mean a lot until she followed it with her first-round defeat of 24th seed Kaia Kanepi in her first round at Melbourne Park.
Muguruza maintained the form in her second-round match and then scored the best win of her career in the third round, coming from a set down to knock out former world No.1 Caroline Wozniacki.
"I was really prepared for big fight," she said.
"So I had to fight too, and keep fighting."
It was an attitude she developed while recovering from a fractured ankle that interrupted a barnstorming 2013 season in which she took her ranking from 104th in the world to 53rd.
"I started to play on a chair and then it was a little bit more until I was normal," she said.
"I was like a big bull at home ... I thought `when I go back to the tournament I'm going to fight so much'.
"So that's what I did."
Muguruza, who moved with her family to Spain as a youngster, has also overcome another obstacle that affected her first Australian Open campaign last year.
In only her second grand slam appearance, she met Serena Williams in the second round at Rod Laver Arena, the venue for her third-round win on Saturday and for Monday's fourth round.
"It is difficult to play out there in the beginning because it's a very big court with a lot of space around it and you have to be concentrated," she said.
"But now I won out there on the centre court, so it's okay for me."
Muguruza is approaching her meeting with Radwanska with a mixture of hope and confidence.
"I don't want to think about Radwanska yet," she said after her third-round win.
"Later we focus on the tactic to see what's the key to winning."
In Monday's other fourth-round matches, Jankovic faces Romanian 11th seed Simona Halep, Sharapova plays 20th seed Dominika Cibulkova of Slovakia and Azarenka plays American 13th seed Sloane Stephens.