The Survation poll commissioned by the "Better Together" pro-union campaign gave them 47 per cent support against 40.8 per cent for the nationalists, with nine per cent undecided and 3.2 per cent refusing to say.
Excluding undecideds, the "No" to independence camp has 54 per cent and the "Yes" campaign 46 per cent.
With just five days until voters go to the polls, 93 per cent of 1,004 respondents questioned by telephone between Wednesday and Friday said they were certain to vote.
"No-one can afford a protest vote. Any one of us could cast the vote that makes the difference between the UK staying together or breaking apart."
A spokesman for "Yes Scotland" added: "There is everything to play for, and this will spur on everybody who wants and is working hard for a Yes to redouble their efforts.
