Officials from the FIA and the ACO have confirmed a provisional eight-race schedule for the 2019-20 World Endurance Championship season, with Bahrain and Sao Paulo returning to the series' calendar.

Following the shift to a winter schedule for 2018-19 that allowed the 24 Hours of Le Mans to remain the final round of the season, WEC organisers have opted to stick with this format for the 2019-20 campaign that will start at Silverstone on September 1 next year.

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The calendar sees previously dropped races in Bahrain and Sao Paulo return, while Sebring is listed as a TBC round ahead of its first WEC race since 2012 that will take place next spring.

One of the most dramatic changes to the schedule sees the introduction of varied-length races. Straying from the existing six-hour format for all rounds except Le Mans, new four-hour and eight-hour long races have been added to the schedule. Silverstone and Shanghai will both be four-hour events, while the returning Bahrain round will be eight hours long.

WEC CEO Gerard Neveu confirmed in a news conference at Silverstone that the Shanghai race weekend could shift forward to November 10 in order to avoid a clash with the Macau GT event on the November 17 weekend, with the finer details on the calendar set to be confirmed in the coming months before it is ratified by the World Motor Sport Council.

The WEC will also look for a replacement round in North America should the planned race at Sebring not go ahead in 2020.

FIA World Endurance Championship Provisional 2019-20 Calendar

1. 4 Hours of Silverstone - September 1
2. 6 Hours of Fuji - October 13
3. 4 Hours of Shanghai - November 17
4. 8 Hours of Bahrain - December 14
5. 6 Hours of Sao Paulo - February 1, 2020
6. 1000 Miles of Sebring - March 2020 (date TBC)*
7. 6 Hours of Spa-Francorchamps - May 3, 2020
8. 24 Hours of Le Mans - June 13-14, 2020

* To be confirmed