Blast from the past

Serena Williams blasted past Simona Halep to set up an Australian Open semi-final showdown with Naomi Osaka, as Novak Djokovic continued his quest for a ninth title in Melbourne with victory over Alexander Zverev.

Williams took a step towards a record-equaling 24th Grand Slam title with a 6-3, 6-3 dismantling of Romanian second seed Halep, the American's nemesis in the 2019 Wimbledon final.

Williams, 39, said her level was improving ahead of her meeting with Japan's Osaka, who came out on top in their tempestuous 2018 US Open title match.

"Definitely think this is the best match I have played this tournament," the 10th seed said after her win over Halep. "Obviously I had to, going up against the number two in the world, I knew I had to do better."

Their semi-final promises much after Osaka, the reigning US Open champion, looked in great touch in her 6-2, 6-2 win over Taiwan's Hsieh Su-wei.

Displaying great focus against Hsieh, ranked 71 and playing her first Slam quarter-final aged 35, Osaka hit 24 winners and was on court for only 66 minutes. "I told myself just to be really intense from the beginning," said the 23-year-old. "I knew I couldn't afford to be lazy with my footwork or anything."

And Djokovic outlasted Germany's Zverev 6-7 (6/8), 6-2, 6-4, 7-6 (8/6) to set up a clash with 114th-ranked Russian Azlan Karatsev, who became the first man to reach a Grand Slam semi-final on debut when he ousted a hobbling Grigor Dimitrov 2-6, 6-4, 6-1, 6-2.

Qualifier Karatsev, 27, has knocked out three seeds on his run to the last four. "It's an unbelievable feeling," said Karatsev, whose career so far has been badly compromised by injury. "It was tough at the beginning for me to hold my nerves, but I tried to find a way to play."

Karatsev becomes only the second qualifier to reach the Australian Open semi-finals after Bob Giltinan in 1977. He is also the lowest-ranked man to make the semis at a Slam since 125th-ranked Goran Ivanisevic at Wimbledon in 2001.