Six-times champion Serena Williams has overcome a patchy serving display and a searching challenge from Czech Barbora Strycova to book her spot in the quarter-finals of the Australian Open.

Second-seeded Williams needed eight set points before finally clinching the opening set with a bizarre miss-hit winner.

The holder of 22 major titles went on to win 7-5 6-4 despite only getting 45 per cent of first serves into play against the 16th-seeded Strycova.

“It was a really good match from me and I’m glad I got through it,” said Williams. “I wasn’t serving my greatest today and she was getting a lot of returns in there.”

The American has advanced to at least the quarter-finals at the past 10 majors.

The 35-year-old has also reached the quarters 11 times overall at the Australian Open.

Williams will face either red-hot British ninth seed Johanna Konta or Russian Ekaterina Makarova in the last eight on Wednesday at Melbourne Park.

The thing about Zverev

Roger Federer needs no introduction. His surprise Australian Open quarter-final opponent is a different story altogether.

Mischa Zverev grew up in Russia with parents so poor they couldn’t even afford to give him a sibling to play with.

Almost 20 years on, Zverev now has a teenage brother he credits for helping inspire his career-best run at Melbourne Park.

The night before Mischa turned the Open draw upside down with his earth-moving fourth-round defeat of world No.1 Andy Murray, 19-year Alexander Zverev fell painfully short of pulling off his own shock victory over the great Rafael Nadal.

He may have exited the draw, but Alexander Zverev remains very much central to Mischa’s uplifting journey to the last eight of a major for the first time at 29.

Rated by many as a future world No.1 and grand slam champion in waiting, the younger Zverev was the player tipped for a breakout fortnight at Melbourne Park.

Mischa is just thankful he was even born.

If not for the dissolution of the Soviet Union in 1991, which gave his parents the chance to leave for Germany to make a better life, “Sascha” would not have come along.

It wasn’t until their parents learnt a new language and established themselves after working dawn til dusk that they were financially stable enough to provide Mischa with a brother.

Germany’s Mischa Zverev played the game of his life against Murray.

“My brother really pushed me and made me work hard again and try to do the best I can,” Mischa Zverev said, two years after spiralling outside the top 1000.

“I can tell you it wasn’t easy when I came back from wrist surgery. It was my brother who said, ‘You can make it back, you can be top 100 again, be a great player’. I have to say thank you to him quite a lot.

“I was ranked very, very low. It wasn’t easy.

“But having such a great family where my brother’s doing well, the whole family’s there to support you, it was a long journey, but it was a fun one.

“When you see him doing well, there’s a lot of positive emotions in the family on the court, off the court.

“Even when I feel like I’m not doing too well, he’s playing finals in Halle (last year), beating Roger in the semis, it just gives me just positive emotions that I take with me to the next tournament and do well there.”

The world No.50’s reward is a date with Federer on Tuesday on one of the sport’s biggest stages for a nigh-on unthinkable place in the Open’s final four.