Last year's beaten finalist Daniil Medvedev is safely through to the second round at the Australian Open.
The world number five won the last two sets to beat Kasidit Samrej in five sets.
Ninth seed Andrey Rublev crashed out to a straight sets defeat against Brazilian Joao Fonseca.
Alex de Minaur, Taylor Fritz and Holger Rune were among the seeds to progress.
Ons Jabeur's beat Anhelina Kalinina in straight sets.
Italian fourth seed Jasmine Paolini also won in straight sets against China's Sijia Wei.
Elena Rybakina, Emma Navarro and Daria Kasatkina are all through to round two after winning on day three.
Madison Keys advanced after a straight sets victory over Ann Li.
Emma Raducanu advanced, despite recording 15 double faults in her 7-6, 7-6 win over Ekaterina Alexandrova.
