London - Jamie Chadwick's defence of her W Series title has been thrown into uncertainty by coronavirus and the rescheduling of the German Touring Car (DTM) championship the all-female single-seater series supports.
The DTM issued a new provisional calendar on Wednesday with the first half of its season postponed and a tentative start at the Norisring in July and finale at Italy's Monza circuit on November 13-15.
The 10-round 2020 season had been due to start at Belgium’s Zolder circuit on April 24-26.
W Series, which aims to help women racers up the motorsport ladder and will offer Formula One superlicence points for the first time this year, had been due to start in Russia at the Igora drive circuit near St Petersburg on May 29-30.
The Norisring would have been the fourth round of the original eight-race W Series calendar, with the last two races supporting Formula One grands prix in Texas and Mexico in October.
The Formula One calendar has also been ravaged by the virus and is yet to start after the March 15 opening race in Australia was cancelled.
Six F1 races have been postponed and May's Monaco showcase cancelled.
"We at W Series are continuing to discuss our position with DTM, F1 and the (governing) FIA," a spokesman said.
"Given the uncertainty surrounding COVID-19, we will not confirm a 2020 calendar until we have completed those discussions."
Inclusion on the F1 race schedule had assumed the DTM championship involvement would be finished by then and the extension of the touring car calendar complicates matters for the W Series if it is to have a full season.
The Formula One calendar could be radically revised too, however, with the sport hoping to start in the European summer and cram in as many postponed races as possible between then and December.
Britain's Chadwick won the inaugural season, collecting $500 000 in prize money. She and the top 12 from the 2019 championship are all due to return this year.
The series uses identical 1.8-litre Formula Three cars.