Andy Murray picked up a serious ankle injury during his defeat to Tomas Machac at the Miami Open, which will put him out of action for an "extended spell".
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.