The first of three debates between Donald Trump and Joe Biden is taking place in Ohio and will be moderated by Fox News' Chris Wallace - who has said he wants to remain as invisible a presence as possible.
This debate could represent the strongest challenge of the President's handling of the pandemic; his tax record, as revealed this week; his handling of the Black Lives Matter demonstrations; the criticism he's faced from former staffers and officials; and his hasty nomination of a Supreme Court Justice.
Mr Biden on the other hand will likely be attacked for his mental competency – which President Trump has really zeroed in on throughout the campaign, dubbing him Sleepy Joe and even suggesting, without evidence, that he has dementia and a reliance on medication.
Max Towle spoke to our US correspondent Simon Marks.