Tennis legend Martina Navratilova says Ashleigh Barty better hope Petra Kvitova has a tough day at the office – otherwise lightning may strike twice at Melbourne Park.

A year after Kvitova crashed the Barty party at the 2019 Australian Open, the two clash again in the quarter-finals on Tuesday.

Despite losing her past three matches to Barty since clubbing her 6-1 6-4 at the Open 12 months ago, Kvitova remains favourite against the world No.1, according to Navratilova.

“She can hit you off the court. You can play well and still lose because Petra is the boss on the court,” the 18-times grand slam champion told AAP.

“So it will be a trick for Ash to get the ball into play on Petra’s serve and neutralise the serve as much as possible and then to make Petra move.

“When Petra is set for her shots, she really dictates. She’s a fierce ball-hitter and when she gets on top of a point, it’s hard to get back.”

Navratilova is an unabashed admirer of her fellow Czech left-hander and would love to see the dual Wimbledon champion go one better than last year’s finals loss to Naomi Osaka.

“But Ash has got that great slice that’s uncomfortable for Petra,” said the former world No.1.

“Being tall, it’s going to be low for her and draw her into the court, so it’s going to be a great tactical match for both players.

“Ash needs to hope that Petra’s not on because, when she’s on, she’s so streaky she will win four games in a row and you haven’t hit a bad shot.

“But at the same time she can also miss four games in a row. You need to look for your opportunities and take them when they arrive.”

The winner will face either American 14th seed Sofia Kenin or Tunisia’s first-time grand slam quarter-finalist Ons Jabeur in the semi-finals.

Chasing a record-equalling seventh Open crown, Roger Federer takes on unseeded American Tennys Sandgren in his 15th quarter-final in Melbourne.

Reigning champion Novak Djokovic plays big-serving Milos Raonic in the second men’s quarter-final on Tuesday night.