Australian Open: Women's top seed Inga Swiatek safely past Camila Osorio into third round at Melbourne

Women's hot favourite Iga Swiatek and men's darkhorse Jannik Sinner have swept into the third round of the Australian Open, as the weather continued to wreak havoc at Melbourne Park.

World No.1 Swiatek overcame Camila Osorio 6-2 6-3 under the roof on Rod Laver Arena and Italian Sinner waltzed past Tomas Etcheverry 6-3 6-2 6-2 on the similarly protected John Cain Arena.

Rain kept the players off the outer courts for four hours after the scheduled start, adding to fixture congestion triggered by extreme heat and storms on Tuesday, when nine matches could not start and two were not completed.

Maria Sakkari celebrates matchpoint at the Australian Open
Maria Sakkari celebrates matchpoint at the Australian Open. Photo credit: Getty Images

Swiatek headlined the early action that was possible and was the first to admit that the scoreline did not reflect the difficulty of her contest against the 21-year-old Colombian.

The Polish top seed set off at a canter and was 4-0 up, before Osorio found her range with her groundstrokes and scooted around the court to put huge pressure on Swiatek's serve.

Two breaks of serve got the Colombian on the scoreboard at 5-2, but Swiatek broke back to win the opening set and fended off another breakpoint in the opening game of the second.

"It was really intense physically and Camila was running to every ball, she didn't give up," said Swiatek.

"She didn't give me many points for free, so I needed to really work for each one of them, but I'm happy that I was consistent in being proactive and trying to just play a little faster to put pressure."

Swiatek always had the measure of Osorio's serve and even when she was broken serving for the match for the first time, a third round meeting with former US Open champion Bianca Andreescu or Cristina Bucsa never looked in doubt.

Greek sixth seed Maria Sakkari had a much bigger scare against 18-year-old Diana Shnaider on Margaret Court Arena and was forced to come from a set down to beat the Russian teenager 3-6 7-5 6-3 over more than two-and-a-half hours.

"It was a very high level from both of us,"said Sakkari, before joking that Shnaider should consider giving up her college eligibility in the United States and turn professional.

"She played an amazing match, she's very talented, very promising." 

Sinner, who has reached the quarter-finals of all four Grand Slams, but never gone any further, could hardly have shown better form, as he briskly dismissed Argentine Etcheverry.

Strong and aggressive, the 21-year-old fired 32 winners and converted all five breakpoints in 1h 44m to set up a third-round meeting with Lloyd Harris or Marton Fucsovics.

"For sure, the level today was good," he said. "I served well, I returned good as well, as I think he is a very good server, so I'm very happy to be in the next round.

"I'm very happy to play on this court with the roof. Hopefully, it won't rain in the next days."