Tallon Griekspoor of the Netherlands beat Miomir Kecmanovic of Serbia 6-7 (5/7), 6-4, 6-3 to book a second-round meeting with top-seeded German Alexander Zverev, who heads a field missing world No 1 Jannik Sinner as he serves a three-month drugs ban at Indian Wells on Wednesday.
China's Bu Yunchaokete defeated American Nishesh Basavareddy 7-5, 6-4 to book a second-round match against Russian fifth seed Daniil Medvedev, runner-up the past two years to Carlos Alcaraz – who is seeded second as he chases a rare three-peat.
Japanese veteran Kei Nishikori, who revealed during the Australian Open that he almost quit tennis last year after lengthy battles with injury, defeated Spain's Jaume Munar 6-2, 5-7, 7-6 (7/3) to line up a second-round match against 18th-seeded Ugo Humbert of France.
Nishikori was treated for a leg injury in the third set and then soldiered through cramp to close out the victory.
"It was not easy," Nishikori said. "In the third set I was cramping pretty badly, but somehow I came back and won, so a very good match."