London: Maria Sharapova endured her toughest match of the tournament so far at Wimbledon but still made it through to the quarter-finals with a 6-4, 6-4 win over Kazakhstan’s Zarina Diyas on Monday.

The Russian fourth seed, who won the 2004 title, has yet to drop a set but came through what was by far her longest match of the tournament in the 97-minute contest on the 11,000-seater Court One.

She faces Coco Vandeweghe in Tuesday’s quarter-finals after the US world number 47 knocked out Czech sixth seed Lucie Safarova, last month’s beaten French Open finalist, their fourth round encounter.

Sharapova had a nervy start against world number 34 Diyas and was 3-1 down in the second set but the 28-year-old’s experience told and she looked delighted at the end.

“The further you go, the tougher it gets. My opponent is a really good grasscourt player, stayed really low and hit so hard so I really had to be ready for all her shots,” Sharapova said.

“Coming into this tournament, I didn’t have a warm-up event and I wanted to start off strong and give a good chance for myself.

“I thought I’ve been doing good but as we all know, it only gets tougher from here.

“It’s a great position to be in. I lost at this stage last year so was extremely happy to go a round further and continue.”

The Siberian won Wimbledon 11 years ago but has only made it past the fourth round once since 2006.

Sharapova is one of just two top 10 players left in the tournament along with world number one Serena Williams after fifth seed Caroline Wozniacki was beaten 6-4, 6-4 by Spain’s Garbine Muguruza.

Vandeweghe and Madison Keys proved that when it comes to American tennis, there is life beyond the Williams sisters as both reached the quarter-finals.

Vandeweghe used her powerful game to drastic effect to beat Czech sixth seed Lucie Safarova 7-6(1) 7-6(4).

Keys, seeded 21, recovered from a set down to beat Belarussian qualifier Olga Govortsova 3-6 6-4 6-1.

While 20-year-old Keys is already being tipped as the player most likely to fill the void when the Williams sisters call time on their glittering careers, Vandeweghe, a couple of years older, has taken longer to realise her potential.

Having taken care of Czech world number 11 Karolina Pliskova in the second round and demolishing former US Open champion Samantha Stosur in the next to surpass her best grand slam run, she again rose to the challenge against left-hander Safarova.

She described her performance as her worst of the tournament so far, but there was still plenty to enthuse about, not least a formidable serve and some net-skimming drives to the baseline that nearly knocked Safarova off her feet.

“I didn’t really feel that good,” the New York-born 23-year-old told reporters. “I thought it was one of my worst matches that I played the whole tournament so far.

“Serve was kind of in and out. I mean, it was there when I needed it, especially towards the end.” Tellingly, she no longer regards beating a top-10 opponent as a big deal any more.

“It’s a match win. I mean, if we’re going to go by upsets, I have already had three. It’s just another win,” she said.

When it comes to sporting DNA has good stock.

Her mother Tauna, a real “60s child” according to Vandeweghe, who gave her four children nicknames Coco, Beau, Honey and Crash, was a former Olympic swimmer while her grandfather played for the New York Knicks in the ‘50s.

Her late grandmother won a Miss America title.