British number one Johanna Konta retired midway through her Australian Open first-round match with an injury.
The 13th seed had won the first set 6-4 and left the court for treatment before falling 2-0 behind in the second and conceding to Slovenia’s Kaja Juvan.
Meanwhile, Cameron Norrie produced an impressive performance to win an all-British encounter against Dan Evans and reach the second round.
Evans, the 30th seed, struggled physically in a 6-4 4-6 6-4 7-5 defeat.
Only Heather Watson is left in the women’s singles after Francesca Jones lost on her Grand Slam main-draw debut.
After making a promising start against American opponent Shelby Rogers, Jones lost 6-4 6-1 to a player ranked almost 200 places higher.
Jones, ranked 245th in the world, was born with a rare genetic condition and has defied the odds to play professionally.
‘I was really worried if I was able to play’ – Watson on injury concerns
Watson, 26, made a winning start at Melbourne Park despite being “worried” a leg spasm would rule her out of Tuesday’s first-round match.
The British number two was one of 72 players who underwent a ‘hard’ 14-day quarantine on arrival in Australia, which left them unable to train outdoors for two weeks.
“I didn’t feel as fit as usual, which is no surprise,” said Watson, who plays 21st seed Anett Kontaveit in round two.
“I’m taking care of my body carefully because four days ago my left leg went into spasm and I couldn’t finish practising.
“I was really worried about if I was going to be able to play my first round here.”
Watson, ranked 60 in the world, had beaten Pliskova in the opening round of last year’s Australian Open.
The Briton, who had lost her sole warm-up match, hit 37 winners and overturned a 3-1 deficit in the second set to force a tie-break, before converting her first match point.
She previously said there was “nothing fun or easy” about the 14-day quarantine.
Players were provided with workout equipment, with Watson sharing videos of herself jokingly doing a hotel room triathlon during her isolation.
Watson has never gone beyond the third round at the Australian Open.