Sloane Stephens powered past world number three Garbine Muguruza as the seeds continued to fall at the Miami Open on Monday.

US Open champion Stephens dominated Spain's reigning Wimbledon champion Muguruza to record a 6-3, 6-4 win and advance to the quarter-finals.

Stephens, the world number 12, will face either Germany's Angelique Kerber or China's Wang Yafan for a place in the semi-finals.

Muguruza had been the highest ranked player left in the women's draw following the early exits of world number one Simona Halep and Caroline Wozniacki in the earlier rounds.

Earlier Monday, Czech fifth seed Karolina Pliskova booked her place in the last eight after opponent Zarina Diyas retired in the second set.

Pliskova was leading 6-2, 2-1 when the Kazakh player abandoned with an injury.

Women 4th rd

• Karolina Pliskova (CZE x5) bt Zarina Diyas (KAZ) 6-2, 2-1 retired
• Sloane Stephens (USA x13) bt Garbine Muguruza (ESP x3) 6-3, 6-4
• Angelique Kerber (GER x10) bt Wang Yafan (CHN) 6-7 (1/7), 7-6 (7/5), 6-3
• Elina Svitolina (UKR x4) bt Ashleigh Barty (AUS x21) 7-5, 6-4

Men 3rd rd

• Fernando Verdasco (ESP x31) bt Thanasi Kokkinakis (AUS) 3-6, 6-4, 7-6 (7/4)
• Pablo Carreno-Busta (ESP x16) bt Steve Johnson (USA) 6-4, 6-4
• Nick Kyrgios (AUS x17) bt Fabio Fognini (ITA x15) 6-3, 6-3
• Denis Shapovalov (CAN) bt Sam Querrey (USA x11) 6-4, 3-6, 7-5