With seconds remaining Dundee seemed certain to profit from Lee Sharp's powerfully headed 86th-minute equaliser in the mayhem that followed the dismissal of Celtic's Vidar Riseth.
Then Larsson pounced on a loose ball from an innocuous throw-in and swept a left foot shot past the Dundee goalkeeper Robert Douglas. The Swede punched the air in front of the massed green-and-white ranks behind the goal, but his relief was shared by many.
Certainly by John Barnes, who had his first defeat as Celtic coach inflicted just 150 yards down the road at Tannadice last Sunday, and who looked certain to be losing further ground on Rangers until Larsson struck.
And the referee John Rowbotham should have been relieved too. Larsson's smash and grab diluted the scrutiny that would have surrounded an earlier shot from the Celtic player, when his Geoff Hurst-style effort crossed the line after it came down off the underside of the bar, but was not given.
But the man who owes Larsson the greatest debt is his friend and fellow Scandinavian, Riseth. The Norwegian midfielder was dismissed for a shocking chest-high tackle on Eddie Annand in the 86th minute and his team were instantly punished.
Dundee's forward Steven Boyack swung over the free kick which James Grady knocked down into the path of Sharp to thump a header past Jonathan Gould.
It seems that Riseth, who was fined pounds 20,000 last season for his red card in the ignominious Old Firm match, has not learned his lesson. Later Barnes admitted his man had got out of jail: "It was a rush of blood from Vidar and he accepts that it was a stupid thing which almost cost us the game - fortunately, we got our just reward," Barnes said. Yet, for so long in this fraught and scrappy game it seemed as if Celtic were going to get nothing. In the first half they became caught up in Dundee's web and were undone by their own over-elaborate passing, which yielded just one chance when Douglas saved Mark Viduka's 40th-minute shot.
Stilian Petrov, the teenage Bulgarian playmaker, had a quiet first match for Celtic while, alongside him, Eyal Berkovic's frustrations became evident in the 57th minute when he missed a golden chance to break the deadlock.
The former West Ham player was released by Lubomir Moravcik's clever pass which beat the offside trap. He seemed destined to lob the exposed Douglas, but all Berkovic could conjure up was a weak finish. Stephane Mahe stepped in 10 minutes later to show the Israeli how it should be done.
The Celtic full-back, booked just minutes earlier for an unseemly spat with Frank van Eijs, wriggled past two Dundee tackles before thrashing a left foot shot high into the net allowing Celtic to finally shake off their shackles.Reuse content