"Sometimes I'm not really recognising anything from the past", Kvitova later told a media conference at Melbourne Park.
The great Rod Laver was there watching, in the stadium named in his honor.
In the second set, Collins seemed to get back on track, holding her first four service games and breaking Pavlyuchenkova on her second service game.
Two of this year's women's quarter-finalists are relatively unknown.
Navratilova says Barty has "a game to bother anybody and she's fit and she's rising to the occasion".
"She took the match away from me and it was very much out of my control. There is absolutely nothing better".
For Kvitova, who won more tournaments than anyone in 2018 - five - Australian Open 2019 is a chance to get back on track at the Grand Slam events. Williams won their next U.S. Open encounter in the quarterfinals past year.
Her real test came in the fourth round when she met Maria Sharapova. After her Wimbledon shock, she had joked that she have to skip Grand Slam tournaments in future. She battled into the semi-finals in 2012, only to lose in three sets to Maria Sharapova.
"There's never a lonesome moment on the [cricket] field if you're struggling".
"I needed to take that time away", she said, reflecting on her time out playing cricket.
"I always wanted to come back and play on the highest level I can, compete with the best, play the Grand Slams, actually be very deep in the Grand Slam, which is happening". She has been thriving off the home support in Melbourne.
As she paused to take in a breath and wipe away tears, the encouragement and cheers from the crowd intensified and reached a crescendo after nearly 20 seconds to allow Kvitova to respond to Jim Courier's question.
Kvitova had to miss the Australian Open in 2017 because she was still overcoming injuries to her left hand that she sustained in a home invasion the previous month at her place in the Czech Republic. "Time and time again she proves she will fight until the last point".
Barty said was planning a celebratory beer rather moping around after having her gallant Australian Open title bid come to a shuddering halt at Melbourne Park.
"I wasn't nervous at all, I was excited", Barty said.
Ashleigh Barty with kids from the Goolum Goolum Aboriginal co-operative in regional Victoria before her practice session. Meanwhile, Pavlyuchenkova made 25 and dropped to 0-5 in Grand Slam quarterfinals. "Sometimes I'm not really recognizing anything from the past".
Far more controlled from the baseline, Collins was dictating play and won seven straight games before Pavlyuchenkova broke the run, but it was far too late. There are matches when I am nervous, but I can't really do anything with that. After going down in the first set, she moved on to stage a remarkable comeback and knock out the Russian star with 4-6, 6-1, 6-4.
"Petra took the crowd out of it, as well".
But Barty wasn't getting ahead of herself. Mark Edmondson was the last Australian man to win the title, when he beat fellow Aussie and defending champion John Newcombe in 1976. "I'm in the quarterfinals, let's see what happens now".
It is quarter-final time at the Australian Open and what a match this should be.