However, some polls suggest that as many as a quarter of Scotland's 4 million voters remain undecided.
Read MoreScotland independence: Widnae it work?
The television debate, the first of the campaign, pits Salmond, fast-talking leader of the pro-independence Scottish National Party, against Alistair Darling, the head of the "Better Together" campaign.
Darling was also finance minister in the last British Labour government, led by fellow Scot and "No" campaigner Gordon Brown.
Pundits say Salmond, 59, the most senior politician in Scotland's devolved government and the driving force behind the "Yes" camp, is favorite to win the two-hour debate, despite the gap in the polls, because of his powerful rhetorical skills.
Darling, 60, is viewed as a safe and steady, albeit somewhat uninspiring, representative for the "No" campaign, although he and the Labour party command considerable authority in Scotland.
The latest opinion poll, by Survation, showed that 46 percent of voters would back the "No" campaign and 40 percent will vote "Yes", with 14 percent saying they hadn't decided. Some polls show up to a quarter undecided.
Read MoreIndependent Scotland means a 'race to the bottom'
Glasgow's successful staging of the Commonwealth Games, which closed on Sunday, had been seen by some as a chance to attract more "Yes" voters but appears to have had little impact.
The "Yes" campaign says Scotland, which has its own parliament but lacks substantial tax-raising powers, would be freer, better governed and richer if it went it alone.