The Formula One teams have finally been handed a provisional calendar for 2013, but with a number of uncertainties.

The calendar again features 20 grands prix, starting in Australia on March 17 and ending in Brazil on November 24, but with four races in between that have question marks against them.

The new Grand Prix of America in New Jersey has been given a date of June 16, but doubts remain as to whether that race will go ahead.

The German Grand Prix is scheduled for July 21 at the Nurburgring, but the circuit has run into financial difficulties this year, and the race could yet be switched to Hockenheim as a back-up.

As for Singapore, the only night event and one of the highlights of the calendar, a press conference is scheduled for 7pm local time tomorrow (noon in the UK) with confirmation expected as to whether a new contract has been signed, with this weekend's race the last of its initial five-year deal.

As for the Korean Grand Prix, again contractual issues plague that particular race which has faced difficulties since it first appeared in F1 in 2010.

Overall, there are eight back-to-back races next year, a punishing schedule for all the teams and F1 personnel involved.

There will be only one event in Spain from 2013. Valencia had been the venue for the European Grand Prix but that event has now been dropped from the calendar, with Valencia alternating with Barcelona as host of the Spanish Grand Prix from next year onwards.

There will only be seven GPs in Europe next year, the lowest total since 1969.

Provisional 2013 Formula 1 calendar
Mar 17 Australia (Melbourne)

Mar 24 Malaysia (Sepang)

Apr 14 China (Shanghai)

Apr 21 Bahrain (Sakhir)

May 12 Spain (Barcelona)

May 26 Monaco (Monte Carlo)

Jun 9 Canada (Montreal)

Jun 16 America (New Jersey) *

Jun 30 Britain (Silverstone)

Jul 21 Germany (Nurburgring)*

Jul 28 Hungary (Hungaroring)

Sep 1 Belgium (Spa)

Sep 8 Italy (Monza)

Sep 22 Singapore (Marina Bay) *

Oct 6 Japan (Suzuka)

Oct 13 Korea (Yeongam) *

Oct 27 India (Buddh International Circuit)

Nov 3 Abu Dhabi (Yas Marina)

Nov 17 United States (Austin)

Nov 24 Brazil (Interlagos)

* subject to confirmation