Welcome to the BBC's live coverage of the third and final US presidential debate between President Barack Obama and Republican presidential nominee Mitt Romney. The debate starts at 21:00 EST (1:00 GMT Tuesday) and we'll be bringing you minute-by-minute updates, analysis and appraisal from our US and foreign policy experts as well as your tweets and emails.
Foreign policy is the theme of the evening. Pundits expect whole chunks of the evening will be devoted to topics ranging from the threat of a nuclear Iran and escalating violence in Syria, to an emerging China and the debt crisis in Europe.
The 90-minute debate is taking place at Lynn University in Boca Raton, Florida. With 15 days to go until the election, Florida is one of a handful of key swing states considered to be still up for grabs - and with 29 electoral college votes, Florida is a prize the candidates are clamouring to win. Have a play around with our electoral college calculator to see the various roads to the White House.
Veteran TV anchorman Bob Schieffer of CBS News will be moderating the debate, and pundits say his performance tonight will be closely watched too. CNN's Candy Crowley and Jim Lehrer of PBS were both criticised after the first two debates for intervening too much and too little respectively.
Schieffer is going to take the candidates through six 15-minute segments, addressing a different foreign policy issue in each part. After asking the candidates a question, each man will have two minutes to answer, and then the moderator will guide the discussion from there. Romney gets the first response and the last closing statement - as decided by separate coin tosses.
Pundits say that what happens on stage tonight couldn't be more important - even though voters generally don't care as much about foreign policy as they do about jobs and the economy.
And, you can have a look at our poll tracker to see how the candidates have fared in recent weeks - and to remind yourself of how tight this race is shaping up to be.