The First Minister and his top team will be in Portlethen on February 24 while the Prime Minister and his are also expected to be in North East Scotland on the very same day.
While No 10 was tight-lipped, the speculation is that Mr Cameron and his Cabinet will be just seven miles away in Aberdeen on that date, visiting local businesses, including the oil and gas industry, and making a number of announcements.
A Downing Street source, asked if the speculation was true, did not deny it but replied: "We are not confirming a date or a venue; these will be announced in due course."
Whitehall said some time ago the Prime Minister and his colleagues would venture to Scotland for the first ever Coalition Cabinet north of the border ahead of the September referendum. Gordon Brown, Mr Cameron's predecessor in No 10, held one in Glasgow in 2009, which was, at the time, the first Cabinet meeting in Scotland since 1921.
The news the PM would fly to Scotland in three weeks' time prompted Mr Salmond to write yet another letter to Mr Cameron, welcoming the "happy coincidence" and saying it would provide an "ideal opportunity" for them to debate.
"The Prime Minister claims the reason he doesn't want to debate independence is because he is too posh for Scottish voters' tastes; but that's an excuse that simply doesn't wash," declared the SNP leader.
Insisting Mr Cameron should have the "courage of his convictions", Mr Salmond added: "We now have six polls in a row showing movement toward a Yes vote; put simply, Mr Cameron has nowhere left to run. Will he finally accept this challenge to a head-to-head debate; or is he still feart?"
No 10 recently made clear that however many times Mr Salmond asked for a PM versus FM debate, the answer would be a firm no.
Last night, a Downing Street spokesman offered another rebuff, saying: "The Prime Minister's position on a head to head with Mr Salmond is still the same; there is no change."
Last month, Mr Cameron claimed the only reason the First Minister was repeating his debate challenge was because he was "losing the current argument and he wants to try and change the argument."
Yesterday, Mr Salmond pointed out how news of the UK Cabinet's meeting to Scotland came as a poll was published, which showed 67% of people thought Mr Cameron should debate the key issues with him while just 17% disagreed.
The same poll, conducted by TNS, placed the Yes vote on 29%, up two, and the No vote on 42%, up one, with don't knows on 29%, down four. When the don't knows are stripped out, the Yes vote becomes 41%, up two, and the No vote, 59%, down two.
Elsewhere, Mr Carmichael attacked the language used by the Yes camp as "quite disgraceful".
The Scottish Secretary said: "Talking about fees refugees swamping Scottish universities; that helps nobody. It's quite deliberate; it isn't done by accident."
He added: "I have been called a quisling and any number of things like that. It is offensive not just to me - I have broad shoulders, I can take it - but to our neighbours, who suffered under Nazi occupation. To compare Scotland as part of the UK to their situation is offensive."
But Blair Jenkins for Yes Scotland claimed the "over-the-top language" had been far more pronounced from the No camp.
One pro-UK politician had, he said, "talked about 'bayoneting the wounded' after the referendum. Scottish politicians and English politicians have compared Alex Salmond to Mussolini, Hitler, the North Korean chap, Mugabe. There's nothing that comes the other way like that".