MELBOURNE: Former world number one Karolina Pliskova conceded she played far from her best tennis at the Australian Open on Thursday, but excelled in clutch moments to avenge a loss to Danielle Collins in a warm-up tournament just eight days ago.

Pliskova, seeded sixth, lost serve twice in a see-saw opening set but pulled away in the second to book a place in the third round with a 7-5 6-2 win over American Collins, a 2019 Australian Open semi-finalist.

After winning last week's contest at the Yarra Valley Classic in two tightly-contested tiebreakers, Collins leaked errors from her normally reliable forehand, allowing Pliskova to take control late in the first set.

"I don't think was really good quality today. I think I just played better in some moments, which I didn't last week," Pliskova said.

"I knew if I just play at least similar as I was playing last week, I knew it's going to be difficult for her to repeat what she played last week.

"It was more about like staying positive, staying in there. I knew I'm going to have some chances, which I did."

Up next for Pliskova, who is chasing her maiden Grand Slam title, is fellow Czech and 25th seed Karolina Muchova.

The two are friends off the court and practised together during a mandatory two-week quarantine period before the Australian Open.

"Even if we would not practise those two weeks in quarantine, we practice a lot in Czech. We're actually quite good friends," Pliskova said.

"Of course, she's a dangerous player. It's going to be very tricky."