Naomi Osaka added another prestigious scalp to a growing list, while Roberta Vinci brought her career to an end in Rome.
It was not an easy win, but Simona Halep beat Magdalena Rybarikova at the Stuttgart Open where Angelique Kerber was also a Wednesday winner.
Petra Kvitova put the Czech Republic through to the Fed Cup final and they will face the US, thanks to Sloane Stephens and Madison Keys.
The Czech Republic hold a 2-0 lead over Germany in their Fed Cup semi-final after a productive opening day in Stuttgart.
Jelena Ostapenko's error count was simply too high as she lost to Sloane Stephens in the final of the Miami Open.
Jelena Ostapenko will face Sloane Stephens in the Miami Open final after overcoming Danielle Collins.
At 6-3 2-0 down things were looking bleak for Sloane Stephens, who produced a sensational fightback to defeat Victoria Azarenka in Miami.
Angelique Kerber struggled in the Miami wind, but Sloane Stephens had no such troubled as she eased to victory in just over an hour.
Venus Williams – a three-time winner in Miami – eliminated the defending champion following a gruelling three-set battle on Monday.
For the sixth time in 11 meetings, Simona Halep went down to Agnieszka Radwanska.