The 2021 Shanghai Masters, Chengdu Open and Zhuhai Championships - all ATP Tour 250 competitions - have been cancelled due to COVID-19.

Another ATP 250 event, the Maharashtra Open in Pune in India, has announced its cancellation after being postponed earlier in the year.

To replace these, there will be an ATP 250 tournament in Nur-Sultan in Kazakhstan on indoor hard courts in week 38 - September 20 to 26 - and an ATP 250 event in San Diego on hard courts at the Barnes Tennis Center from September 27 to October 3.

The rescheduled Indian Wells Masters will also be extended to become an 11-day event later in October.

The ATP 250 St Petersburg Open moves to week 43 - October 25 to 41 - alongside the Vienna Open.

The ATP Tour is set to reach its climax at the ATP Tour Finals in Turin in November, before the offseason break until the build-up to the Australian Open in January 2022.

Andrea Gaudenzi, ATP Chairman, said: "We’ve maintained a flexible approach to the calendar this year due to the constantly evolving nature of the pandemic. 

"It’s extremely unfortunate to announce the cancellation of our Asia swing this season and we look forward to returning in 2022. 

"I would like to thank all tournament operators for taking on the challenge of staging in this environment, including the new single-year event operators that have stepped up. 

"Players also deserve huge credit for putting on a world-class spectacle for fans week-in and week-out, as we build toward a thrilling finish to the season in Turin."