Brady goes from hard quarantine to Australian Open semis

Brady was a picture of anguish early in the clash on a stifling day at Rod Laver Arena but gradually dialled in her power game before crushing Pegula in the final set.

Jennifer Brady battled through her frustrations to overhaul friend and the United States teammate Jessica Pegula 4-6 6-2 6-1 and reach her maiden Australian Open semi-final on Wednesday.

Jennifer Brady of the US in action during her quarter-final match against Jessica Pegula (REUTERS)

Brady was a picture of anguish early in the clash on a stifling day at Rod Laver Arena but gradually dialled in her power game before crushing Pegula in the final set.

The 22nd seed has a golden chance to reach her first Grand Slam final after world number one Ash Barty was shocked by Karolina Muchova in the early quarter-final on Wednesday.

With Serena Williams to face Naomi Osaka in the other semi-final, the Australian Open could have another all-American title match on Saturday, four years after Serena beat her sister Venus for the 2017 championship.

Having long flown under the radar, 25-year-old Brady also reached the semi-finals of the U.S. Open last year and said she hoped more was to come.

"I hope I make it a habit," she said on court.

"Hopefully I have a new habit of making finals."

Brady's effort is more remarkable for having been one of the 72 players in hard quarantine before the tournament, unable to train on courts for five hours a day like the rest of the field.

Despite the limited preparation and a raft of taxing rallies against Pegula, there was no sign of her flagging in the heat.

After taking the second set, Brady was brimming with confidence and raced away with the match in a maelstrom of shot-making.

"I've been putting in the hard yards in the gym with my trainer Daniel," she said.

"We're getting better every single day, every day is another opportunity."

Pegula, the daughter of billionaire sports team owners, bowed out after reaching her first Grand Slam quarter-final.

Her aggression threatened to produce another upset but her serve faltered in the final set and the hard-returning Brady capitalised.

Brady said she was "delighted" that fans would be allowed back at Rod Laver Arena from Thursday after Victoria's five-day lockdown ended.

"It'll be great to play in front of people, especially the semi-finals," said Brady.

"In New York, it was an empty stadium, so here it will be a new atmosphere.

"I'm really looking forward to it."