Johanna Konta safely into last-16 of Miami Open

Johanna Konta moved into the last 16 at the Miami Open after a three-set battle with unseeded Russian Elena Vesnina.

The British No 1 struggled through the first set, but powered back in the second to force what turned out to be a gruelling decider, eventually prevailing 4-6 6-1 7-6 in nearly two-and-a-half hours.

Konta appeared frustrated for much of the opening set and Vesnina made the most of a series of errors to claim the sole break of service in the seventh game.

But Konta responded in the second game of the second set, claiming her first break of the evening before saving a break point as Vesnina attempted to rally.

Konta pulled away during the rest of the set, sealing it with an ace, and she continued to press in the third, eventually securing the first break in game seven.

Vesnina pegged her back straight away, and Konta had to nervously serve to stay in the match at 5-6, forcing a tie-break after a superb rally which included a series of volleys at the net.

Konta dropped a mini-break down in the breaker after missing a backhand volley but she drew level straight away and won four straight points from 3-3 to set up a clash with Romania's Monica Niculescu.

Second seed Angelique Kerber had moments of concern before going through against Kiki Bertens of the Netherlands.

Kerber lost the first set 6-1 to Bertens but responded to take the second 6-2 and was 3-0 up in the third when her opponent retired.

Victoria Azarenka, seeded 13, saw off Poland's Magda Linette 6-3 6-0 but ninth seed Roberta Vinci was beaten 6-4 6-4 by 22nd seed Madison Keys of the United States.