Jannik Sinner, who finished his win over Mackenzie McDonald at 2:37 a.m. Thursday, withdrew after he was scheduled as the fourth match on Court Central.
Tommy Paul will make his fifth straight appearance in Delray Beach.
Olympic gold-medal champion hit with fine of $475,000 by Berlin court. Zverev is contesting the penalty order and denies abuse allegations.
Sanjar Fayziev from Uzbekistan is suspended three years, six months and Israeli Igor Smilansky hit with two-year ban for corruption.
"I played in Bercy much better when there was no crowd at all in attendance," Daniil Medvedev said after falling to Grigor Dimitrov.
World No. 48 Peyton Stearns steps in for Madison Keys, who withdrew from the U.S. squad.
The Russian was the king of the 500s in 2023.
