The Mexican Grand Prix organisers say they have missed a deadline for provisional 2020 Formula 1 calendar inclusion, at a time when five races are in doubt for next year.
The event recently lost its central government support, while the contracts of the F1 races in Spain, Britain, Germany and Italy all expire this season, and no new agreements have been signed. None of them is therefore guaranteed a place on next year's schedule at present.
A statement issued by the Mexican organisers said: "After the deadline to keep the date that we were using for the Formula 1 Mexican GP expired, we would like to communicate that the promoters of the event had lost their preferred rights to keep that date in the 2020 calendar.
"Nevertheless, the negotiations either with F1 and the authorities of our country are still on course with the best spirit to find an alternative to keep the competition in Mexico.
"When we'll have news about the negotiations we are maintaining with the authorities, we'll make it public, only through official channels and spokespersons."
F1 CEO Chase Carey has downplayed the ongoing question marks over the unsigned deals.
"We have contracts where '19 is the last year and we have either to create a new agreement or go our separate ways," Carey told Wall Street analysts and investors. "And there's nothing really unique to this that wasn't true last year.
"We had a number of renewals last year, just as we had a number of renewals the year before. There are different issues in each one."
One source has indicated that F1 and the FIA will discuss the shape of the 2020 season at next week's World Motor Sport Council gathering, which would be earlier than the subject is usually addressed.
Any provisional calendar could still include all five races that are not yet firm listed in their usual slots with an asterisk as 'subject to contract'.
Vietnam is the only new event confirmed so far for 2020, and without agreements with the races in question the calendar could fall below the current level of 21 events.
Carey said there is a lot of interest from potential new races, but he insisted that the priority was to firm up deals with existing events.
"I think the most positive aspect to that is we're increasingly encouraged by the breadth of interest of new parties who want to come in," he noted. "The dynamic that's really important for us is supply and demand.
"Some of our races are long term partners, some are not quite as long. Our first approach, if we can get to a place that works for both of us, is to renew races.
"We're not necessarily always going to be able to get there, but to make sure we're getting fair value it's important that we have alternatives in places that provide not just attractive finances but attractive races.
"An example being Vietnam, we think it's going to be an exciting new place to go, it fulfils the objective of growing in Asia, so it's a win-win for both of us. It really ticks all the boxes."
Carey added that there are possibilities for new races in F1's traditional heartland of Europe, as well as elsewhere.
While he did not specify any countries, the Netherlands remains the most realistic contender for 2020 - with Zandvoort and Assen having both expressed an interest.