The struggling American Sloane Stephens had only slim chances of keeping the title in Miami but they were done and dusted on Sunday night, with Tatjana Maria toppling the 4th seed 6-3, 6-2 in an hour and 33 minutes to reach the last 16.
The German did everything right on the court, mixing up her strokes and forcing Stephens to play from awkward positions, something she wasn't ready for today. Tatjana suffered two breaks of serve but Stephens needed more on the return to stay competitive, giving away half of the points behind the initial shot and five breaks from nine opportunities Maria created.
With no first serve or any idea how to impose her shots, Sloane was just a shadow of a player who claimed the title here 12 months ago, losing the last three games in each set to hit the exit door and drop a massive amount of points to drop out from the top-5.
The 19-year-old Czech Marketa Vondrousova took down the 16th seed Elise Mertens 6-4, 7-6 in just under two hours despite five breaks she suffered, taking the opener with her fourth break of serve at 4-4 and opening a 5-3 lead in set number two.
Mertens made one last push to break back in game ten and set a tie break that Marketa claimed 7-1 after a dominant performance that booked the place in the next round for her. The 5th seed Karolina Pliskova had to stay on the court for more than two and a half hours, prevailing against Alize Cornet 6-7, 6-1, 6-4 to remain on the title course.
The Czech saved eight out of ten break points and despite losing the opening set she was never in doubt in the rest of the clash, creating no less than 21 break points and converting five, wasting a chance to finish the match earlier and reduce the time spent on the court.