Miami Open: Johanna Konta beats Elise Mertens in third round

Johanna Konta will next face Venus Williams or Kiki Bertens

British number one Johanna Konta moved into the Miami Open fourth round with a dominant win over Elise Mertens.

Defending champion Konta, ranked 14th in the world, secured a 6-2 6-1 victory over the Belgian world number 21 in 65 minutes.

The 11th seed will next face 37-year-old Venus Williams, the world number eight.

American Williams defeated 26-year-old Kiki Bertens, of the Netherlands, after saving three match points.

Konta was helped in the first set by Mertens registering six double faults - including four in one game - and she played an almost perfect match as she swept into the last 16.

"I tried to take my game to her and managed to do that for big pockets of time, but it's never easy to come through so I'm really happy," Konta said.

"I definitely have a great relationship with this tournament, the biggest title of my career has come here. Hopefully I can get to the end again."

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Williams came back in style against world number 29 Bertens, winning 5-7 6-3 7-5.

The American raced to a 5-0 lead before losing the next seven games and the first set.

She then won the second set comfortably before an exciting decider that saw Bertens take a 4-1 lead.

Bertens was suffering from cramp in her right arm in the latter stages of the match and appeared to be in tears at one stage.

There were five breaks of serve in the final set before Williams completed her victory.

"I'm not sure how I did that," Williams said. "I had a lot of chances, she had a lot of chances.

"It didn't look good sometimes but that's why you play to the last point. We were in a battle but I'm happy to be coming back tomorrow."

Fourth seed Elina Svitolina made her way through to the next round with a three-set victory over Daria Gavrilova 4-6 6-0 6-1, while sixth seed Jelena Ostapenko defeated Beatriz Haddad Maia 6-2 7-6.

In the men's event, Marin Cilic and Juan Martin del Potro made it through to the fourth round on Sunday with straight-set victories.

Argentina's fifth-seeded Del Potro, chasing his second ATP Masters title in as many weeks, got past Japan's Kei Nishikori 6-2 6-2.

Second-seeded Cilic also reached the fourth round with a 7-5 7-6 (7-4) victory over Canadian Vasek Pospisil.

In the men's doubles, Britain's Jamie Murray and Brazilian partner Bruno Soares were knocked out in the last 16 by Andrey Rublev and Karen Khachanov.

The Russian pair go on to play Croatia's Mate Pavic and Austria's Oliver Marach in the quarter-finals.

In the women's doubles, Konta and fellow Briton Heather Watson lost 7-5 6-4 in their second-round match against Russian top seeds Ekaterina Makarova and Elena Vesnina.