Rafael Nadal stressed he must be "respectful" of the hip injury which kept him sidelined, but is ready to return in the Davis Cup.
World number 11 Lucas Pouille is not impressed by the proposed reform of the Davis Cup, claiming he is prepared to boycott the competition.
Things were going well at the Charleston Open for Petra Kvitova until Kristyna Pliskova roared back to reach the last 16.
A knee operation has further delayed the return of Jo-Wilfried Tsonga, who hopes to be back at some stage during the clay-court season.
Former world number one Novak Djokovic is without a coach heading into the clay-court season.
Garbine Muguruza was a class above as she saw off local wildcard Renata Zarazua 6-1 6-1 on the Mexican hard courts on Tuesday.
Naomi Osaka, a surprise champion at Indian Wells last month, beat Jennifer Brady in her first match of the year on clay.
John Isner won his first Masters title at the Miami Open on home soil, producing a brilliant display of serving to beat Alexander Zverev.
Jelena Ostapenko's error count was simply too high as she lost to Sloane Stephens in the final of the Miami Open.
German fourth seed Alexander Zverev overcame Pablo Carreno Busta in the Miami Open semi-finals.