Presidential debates are a political version of gladiatorial combat and they have, in the past, turned elections.
There are three debates before each election. The first debate in 2016 was watched by a record 84 million people on TV.
That doesn’t include the millions who watched on Facebook, YouTube, and other online venues, or at parties and bars.
For many it was the only time they listened to the candidates speak at length.
Four years ago the polls showed it was reasonably close between Mr Trump and Hillary Clinton with neither delivering a knockout blow. This time Mr Trump sees a chance to obliterate his deficit in the polls in a single evening.
Meanwhile both Mr Trump’s and Mr Biden’s running mates – Mike Pence and Senator Kamala Harris – clashed in their own vice presidential debate on Wednesday night, with the focus dominated by the Trump Administration’s Covid-19 response.
Read more: Vice-presidential debate analaysis
Trump approval static at around 40 per cent
Donald Trump’s presidential approval ratings are at steady levels, according to the Telegraph’s poll tracker.
The tracker, which takes an average of the last eight polls, put Mr Trump’s approval rating at around 44 per cent, while 54 per cent disapprove of the way the President is doing his job.
The President’s approval ratings had recovered slightly recently, after experiencing a “rally around the flag” effect with Americans backing the Government to handle the coronavirus crisis.
The period since Donald Trump’s election has been packed with controversy and intrigue but, underneath it all, few people seem to have really changed their minds about America’s 45th President.