Halep confronts Venus as Serena and Djokovic resume Slam drive

Romania's Simona Halep, who is returning from a herniated disc, has limped through her first two matches at Melbourne Park. (Photo: AFP/Jewel SAMAD)

Halep, who is returning from a herniated disc, has limped through her first two matches at Melbourne Park, taken to three sets in both, and knows she will need to up her game to make the last 16.

"Tough one, but for sure I'm not going to run that much," she said of facing the elder Williams sister, who is still going strong 21 years after playing for the first time at Melbourne Park.

"Because it's going to finish fast, the points. She's a great player, champion. It's always a big challenge for me to face the sisters," she added ahead of the night match on Margaret Court Arena.

Seven-time Grand Slam champion Venus is unseeded, but remains a threat. She made the final in 2017 when she lost to Serena.

Her sister is gathering pace as she targets a record-equalling 24th Grand Slam title and should have little trouble against unseeded Ukrainian teenager Dayana Yastremska in an afternoon match on Rod Laver Arena.

"The key is just going out there and playing really well, just doing the best that you can," said Serena as she zeroes in on a record-equalling 24th Grand Slam singles title.

"I'm not always confident. I just do the work, I go out there and I play the best I can. I work hard and see what happens. That's it."

The sisters will meet in the last 16 if they come through their third-round match-ups.

Fourteen-time Grand Slam winner Novak Djokovic is gunning for a seventh Melbourne Park title and faces 25th-seeded Canadian Denis Shapovalov, one of the NextGen stars who are out to topple the sport's big guns.

"He's very pumped. He brings a lot of energy to the court, which is great to see," said Djokovic said of the 19-year-old.

"I expect a really interesting encounter. He will not have anything really to lose, so I'm sure he's going to come out really pumped."

Whoever wins will play either 21st seed David Goffin or 15th seed Daniil Medvedev for a berth in the quarter-finals.

Others in action Saturday include men's fourth seed Alexander Zverev against young Australian Alex Bolt and US Open champion Naomi Osaka, who plays an all-Asian clash with Taiwan's Hsieh Su-wei.