Petra Kvitova and Bianca Andreescu were the biggest casualties in the second round of the Australian Open as Serena Williams once again breezed through.
Andreescu, seeded eighth as she makes her return from a long-standing knee injury, lost 6-3 6-3 to tricky Taiwanese Hsieh Su-wei.
Williams and Garbine Muguruza were among the winners at Melbourne Park.
American Williams, seeking a record-equalling 24th Grand Slam title, beat Serbia's Nina Stojanovic 6-3 6-0 and will face Anastasia Potapova of Russia next.
Last year's finalist Muguruza continued her good form on the hottest day of the tournament so far with a 6-3 6-1 win over Russian Liudmila Samsonova.