Serena Williams has been included on the entry list for the US Open along with fellow former champion Novak Djokovic, who will not be able to compete due to his refusal to be vaccinated against COVID-19.

Williams, who returned to competition last month after a year-long absence, was added to the entry list for the August 29-September 11 grand slam in New York having been named in the draw for tune-up events in Toronto and Cincinnati.

The 23-times grand slam champion fell in the first round at Wimbledon and last appeared in the US Open in 2020 when the six-time winner reached the semi-finals.

After her Wimbledon exit, Williams said she was very motivated to get better and play at the US Open.

Eligible players are automatically entered into the main draw of the US Open. But that does little to help Djokovic, who defeated Nick Kyrgios to retain his Wimbledon crown last month and is one behind Rafael Nadal’s record of 22 grand slam titles.

Djokovic will not be able to participate in the year’s final grand slam due to current rules under which travellers seeking to enter the US have to be fully vaccinated and provide proof before boarding flights.

“I’m not vaccinated and I’m not planning to get vaccinated so the only good news I can have is them removing the mandated green vaccine card or whatever you call it to enter United States or exemption,” he said.

“I don’t think exemption is realistically possible. If that is possibility, I don’t know what exemption would be about. I don’t know. I don’t have much answers there.”

Djokovic’s comment that he could seek an exemption had raised eyebrows, prompting tournament organisers to release a statement clarifying they would ot seek an exemption for the World No.7.

The US Open said it did not have a vaccine mandate for players, it said, “but it will respect the US government’s position regarding travel into the country for unvaccinated non-US citizens”.

“Per the Grand Slam Rule Book, all eligible players are automatically entered into the men’s and women’s singles main draw fields based on ranking 42 days prior to the first Monday of the event,” it read.

Almost 12,000 people have signed an online petition calling for Djokovic to be allowed to compete in the US Open despite his refusal to have the COVID-19 vaccine.

“There is absolutely no reason at this stage of the pandemic to not allow Djokovic to play at the US Open 2022,” said the change.org petition, which was launched on June 21.

“[The] US Government and USTA must work together to allow him to play … MAKE IT HAPPEN, USTA!”

Djokovic won the Australian Open, French Open and Wimbledon titles in 2021. He was unable to defend his Melbourne Park crown this year after controversially being deported from Australia over his vaccination status in January.

He later said he was prepared to miss grand slam tournaments rather than take the COVID-19 vaccine.

-with AAP