The televised duel will take place from 9-10.30pm on Thursday (1200-1330 AEDT Friday) in Nashville, Tennessee.

The commission responsible for organising the debates has changed the rules for the last match-up, muting one candidate's microphone so the other has two minutes of uninterrupted time to initially answer the moderator's questions. The remainder of each 15-minute segment will be open discussion.

Organisers hope the new rule will prevent the chaos and frequent interruptions that marked the first presidential debate last month.

Trump comes into the final debate trailing Biden in the polls.

The president has repeatedly attacked the debates commission, characterising the event as unfair and accusing moderator Kristen Welker of favouring Biden.

The NBC News reporter has chosen to discuss topics including climate change, national security and the coronavirus.

Trump has come under fire for his handling of the pandemic, which has resulted in more than 221,600 US deaths.

Biden could face questions about his son's past business dealings as Republicans have levelled unverified corruption allegations against him.

The second presidential debate, which was meant to take place last week, was cancelled after Trump declined to participate when it was moved to a remote format due to his coronavirus diagnosis.

Although millions of people have already cast their ballots in early voting, the debate could still change some voters' minds.

Australian Associated Press