Stefanos Tsitsipas struck a huge blow for the next generation by beating two-time defending champion Roger Federer in the fourth round of the Australian Open.

Tsitsipas next faces another first-time Grand Slam quarter-finalist in Roberto Bautista Agut while Rafael Nadal eased past Tomas Berdych and will take on Frances Tiafoe, who celebrated his 21st birthday with an emotional win over Grigor Dimitrov.

Ashleigh Barty became the first Australian woman to reach the last eight here for a decade by knocking out Maria Sharapova and next plays Petra Kvitova while American Danielle Collins stunned second seed Angelique Kerber for the loss of only two games.

Tiafoe has been copying his hero, basketball superstar LeBron James, with his celebrations this week, removing his shirt to thump his bare chest and his biceps.

When ESPN put both versions on their Instagram page, who should reply but James himself.

“He commented ‘silencer’ (the name of the celebration) and he put a crown, two muscle emojis,” said Tiafoe. “I was like, ‘Clearly he knows who I am now. That’s just crazy’.”

Collins has come to wider attention thanks to her stunning run here, but anyone who has seen the American on a court knows that feistiness is her stock in trade.

She said: “I love making it kind of a war. If somebody wants to get in my face on my unforced errors, I have no problem getting right back at them. I just love competition. Sometimes when people are all for me I’m like, ‘I hope somebody says something negative so I can prove them wrong’.”

The big match on Monday has seen title favourite Serena Williams see off world number one Simona Halep in the first match of the night session on Rod Laver Arena, beating her in three sets.

Following that, Novak Djokovic will look to avoid suffering the same fate as Federer when he takes on talented young Russian Daniil Medvedev.

Earlier, US Open champion Naomi Osaka faced Anastasija Sevastova and defeated her in three sets, while fourth seed Alexander Zverev suffered defeat at the hands of Milos Raonic.