SYDNEY - Seven-time Grand Slam singles champion Venus Williams of the United States on Saturday decided to pull out of the Australian Open, only hours after world No 1 men's singles player Carlos Alcaraz of Spain announced his withdrawal.

The official account of the Australian Open said in a social media post that Williams has withdrawn from the Grand Slam due to an injury sustained at the ASB Classic in New Zealand. The wildcard for Williams will be awarded to Kim Birrell, a 24-year-old Australian currently ranked as No 173 in the women's singles.

The Australian Open 2023 was supposed to mark Williams' 22nd trip to Melbourne Park, 25 years after she debuted at the tournament in 1998.

Earlier, world No 1 Alcaraz confirmed that he had to miss this year's Australian Open due to a right leg injury that he picked up "through a chance, unnatural movement in training".

"It's tough, but I have to be optimistic, recover and look forward. See you in the 2024 Australian Open," said the top seed.

With only a few days to go before the Australian Open kicks off, multiple players have reported injuries, adding uncertainties to their performance at the beginning of a new tennis season.

After being smashed by the US player Jessica Pegula 6-2, 6-2 in the United Cup semifinals, world No 1 Iga Swiatek of Poland on Saturday withdrew from Adelaide International, troubled by a right shoulder injury.

On Friday, when facing off Slovakia qualifier Viktoria Kuzmova at the ASB Classic, the 2021 US Open champion Emma Raducanu retired from their match at the start of the third set. The British emerging tennis star was seen leaving the court with tears.

"So to be stopped by a freak injury, rolling an ankle is pretty disappointing, in the first week as well," Raducanu told media, adding that it remains unknown if she'll be able to play at the Australian Open.

World No 22 Nick Kyrgios also withdrew from the United Cup and Adelaide International, two warm-up events before the Australian Open, as the 27-year-old Australian had to recover from an ankle injury.