At the weekend the Deputy First Minister Nicola Sturgeon insisted a feel-good factor from the Commonwealth Games would propel the Yes side.
Mr Miliband said the impetus was against independence as he added that No was winning both heads and hearts, something he also predicted would be seen onscreen when Alex Salmond and Alistair Darling finally go head to head.
No campaigners have faced accusations they have concentrated too much on cold, rational economic arguments for the Union to the detriment of any emotional appeal.
But as the independence fight steps back into the limelight this week with what many will view as the start of the short campaign, Mr Miliband said: "I think we are winning both the head and the heart. I think that argument is being won."
He added: "I'm sure that will be reflected in the debate - and I'm sure Alistair will do a tremendous job."
The two men will take part in another televised debate on the BBC just before postal votes are sent out at the end of this month.
Both sides view the last week in August as a crucial point by which they will have to reach their first "peak". Large numbers of Scots expected to vote by post as soon as they receive a ballot paper.
Ahead of the debate, Mr Salmond has reportedly been receiving help from Claire Howell, the lifestyle coach who has helped him to prepare for previous election, including the SNP's 2011 Holyrood landslide.
Mr Darling has also been preparing intensely, though friends insist he had been doing so for decades.
Both sides are keen to avoid their opponent securing a repeat of "Cleggmania" when the first TV debate of the 2010 General Election briefly allowed the LibDem leader to soar in popularity.
The SNP says the more voters hear the arguments, the more inclined they are to back independence. It is also confident its leader is the better media performer.
However, there is a feeling within the No camp that it has less to prove, although it is keen to preserve its poll lead.
Professor Stephen Coleman, an expert on televised debates from Leeds University, said the event would be "crucially important" for targeting people who do not normally follow political news.
"It's important in two ways - to remind people of the key issues and give people a measure of political leaders," he said.
He added both sides have to avoid talking solely to their supporters.
"My advice would be to think of people having their breakfast in a cafe the next morning or working in that cafe."
Surveys at the weekend suggest that neither campaign received a boost from the Commonwealth Games.
A poll for the Scottish Mail on Sunday, by Survation, put Yes on 40 per cent, down one percentage point in a month, with No on 46 per cent and undecideds on 14 per cent. The poll also found that 37 per cent of those asked thought Mr Salmond likely to beat Mr Darling.
Tomorrow's two-hour-long debate on STV follows months of wrangling between both sides. Mr Salmond initially refused to debate with anyone except the Prime Minister, Conservative leader David Cameron. A stand-off ensued for months after Mr Cameron insisted the discussion should be between two Scots.
Meanwhile, Professor David Bell, a former Holyrood Finance Committee adviser, has criticised the SNP's plans to grow the economy after independence as "unrealistic" while reports suggest the Commons Business Select Committee will this week criticise the SNP's flagship plan to renationalise Royal Mail.
There were also reports of warnings from defence firm Babcock that thousands of jobs on the Clyde could go if Scots expel trident after independence. But the Yes campaign hailed a report by Credit Suisse on the features that "make small, independent countries successful on their own".
l Leader of the Scottish Liberal Democrats Willie Rennie has called on Mr Salmond to disassociate himself from remarks made by a former SNP MSP Lloyd Quinan that if people voted No then they are "bad parents".
A spokesman for the First Minister said: "Abuse has no place in the referendum campaign, whether from Yes or No supporters. Lloyd Quinan is not a member of the SNP - and indeed hasn't been for over a decade. Willie Rennie should check his facts before trying to score political points."