In a topsy-turvy battle between two unseeded players, Collins - who was winless at grand slams prior to the tournament - won 2-6 7-5 6-1 at Rod Laver Arena on Tuesday.

The feisty 25-year-old will next face Czech No.8 seed Petra Kvitova, who ended Ashleigh Barty's captivating Open with a 6-1 6-4 win in the second women's quarter-final on Tuesday night.

Having failed to qualify at Melbourne Park last year, Collins made a giant-killing run to the round of 16 that included victories over three-time major winner Angelique Kerber, former Wimbledon semi-finalist Julia Goerges and 19th seed Caroline Garcia.

Outmatched in the early going, a fired-up Collins screamed "come on" after firing a forehand winner to take the second set and even the ledger.

The third set was one-way traffic with former college tennis player Collins sending down 13 winners and making just one unforced error to take the match in two hours and 16 minutes.

Florida native Collins has had a meteoric rise up the world rankings, breaking into the top 40 last season after starting the year at No.136.

Her coach Mat Cloer had predicted his charge wouldn't wilt under the bright lights and it proved to be the case against a far more experienced opponent.

"My first time playing on Rod Laver. I didn't even practise on here before so this was quite the experience," she said.

"I absolutely love it."

Australian Associated Press