Ashleigh Barty says a defeat to Angelique Kerber in 2018 helped give her the focus to become world number one ahead of their Wimbledon semi-final on Thursday.

The German beat Barty in the final of the Sydney Open in three tight sets and the Australian left the court knowing what she needed to do to get to the next level.

She put that into practice and surged to the top of the rankings, winning the French Open along the way in 2019.

Her hopes of winning a second grand slam face the sternest test yet against Kerber, who has rediscovered the form that saw her win at SW19 just six months after beating Barty in that Sydney final.

"I remember that match well. It was my first final in Australia, in Sydney," she said. "I think that match, I think just one break each set in the final.

"I remember coming off the court and feeling like my level was close, but it wasn't good enough. I was close, but there was that extra step that I needed to take to compete with someone of Angie's calibre in the sense of she doesn't give you cheapies.

"She competes for every single point. She's won grand slams. She knows how to hang tough in brutal moments. That was almost a bit of a reset knowing I'm not far off, but I'm not there yet."

"Maybe some players, they play there four times, five times, I think that's a big advantage, especially here. You can get a warm-up, feel the court.

"Doesn't matter. I played on Court One. I think I did pretty well. Also in this big (press conference) room, so I think things are getting much better."

Sabalenka added: "She's a great player. She's moving well right now. She's hitting balls really solid and serving well. It's going to be tough match but I'm really looking forward for this one.

"I'll do everything I can to win that one."