It's day 2 of the first Grand Slam of the year.
Novak Djokovic and Serena Williams won their matches at the Australian Open.
World number one Djokovic defeated American Frances Tiafoe in 4 sets in their second-round match in Melbourne.
Serena Williams breezed past Nina Stojanovic in straight sets and remains on track for a record 24th Grand Slam title.
However, Serena's sister Venus Williams lost 6-1, 6 love to Sara Errani.
It was far from plain sailing for the world number two Simona Halep, who battled back from 5 games to 2 down in the third set to defeat Ajla Tomljanovic 7-5 in the deciding set of their encounter.
Naomi Osaka had an easier time of it in defeating Caroline Garcia 6-3, 6-3.