Australian Open champion Jannik Sinner recovered from a set down to beat Tallon Griekspoor, while Daniil Medvedev and Casper Ruud also advanced at the Miami Open.
British veteran Andy Murray admitted that the end of his competitive career is nigh, but it's difficult to know when to call time.
Carlos Alcaraz survived a tense opening set to defeat Russia's Daniil Medvedev 7-6(5) 6-1 and defend his BNP Paribas Open title at Indian Wells on Sunday.
Australian Open winner Jannik Sinner continued his unbeaten start to the year with a dominant victory over Thanasi Kokkinakis at Indian Wells.
Rafael Nadal has pulled out of the BNP Paribas Open in Indian Wells as he is not yet fit enough to compete at the highest level.
Alex de Minaur continued his red-hot form in Mexico when he defeated Casper Ruud in straight sets to defend his Mexico Open title in Acapulco on Saturday night.