Formula One races in Mexico and New Jersey are unlikely to happen next year, according to the sport's commercial supremo Bernie Ecclestone.
Both events were on a 22-race calendar published in September but the 83-year-old, speaking at the Abu Dhabi Grand Prix, doubted they would stay on a final version due to be approved by the governing body next month.
Formula One has never had more than 20 races in a season, with this year's calendar running to 19 rounds.
If Mexico and New Jersey fail to make the final version the main novelties will be Austria - returning in June after a decade off the calendar - and a new race in Russia's Winter Olympic venue Sochi in October.
India has been dropped for 2014 and South Korea's race remains doubtful with the local organisers seeking a contract renegotiation for the loss-making event.
Mexico last hosted Formula One in 1992 but recent media reports have suggested the timeframe is too tight to make the necessary improvements to the outdated facilities.
New Jersey, whose 'Grand Prix of the Americas' would have been the second US race on the calendar along with Austin, Texas, has struggled with finances.
