American Sloane Stephens needed just over an hour to cruise past Germanys former world number one Angelique Kerber 6-1 6-2 and reach the Miami Open semi-finals for her first time on Tuesday. The U.S. Open champion fired her 22nd winner on match point to dispatch the 10th seeded Kerber and set up a showdown with three-time champion Victoria Azarenka, who scored a 7-5 6-3 victory over world number six Karolina Pliskova. The win guarantees that 25-year-old Florida native Stephens will make her debut in the top 10 when the WTA rankings are released after the tournament. Tuesdays win was Stephens second straight triumph over a former world number one after she defeated third-seeded Garbine Muguruza to reach the quarter-finals on Monday. Stephens said staying consistent was the key to her win over Kerber.