Dunfermline surrendered their 100 per cent record against Dundee in frustrating style as a bizarre 13th minute own goal by midfielder Barry Nicholson saw the Fifers loose a game that they dominated in every area except the most crucial - the scoreline.
Nicholson had also put through his own goal when the sides last met at Dens Park in November in a match Dunfermline won 3-2.
His latest misfortune proved much more expensive but Dundee were hardy complaining after grabbing their second important win since the winter break.
There was nothing actually wrong with Dunfermline's play from the very start as Jason Dair showed plenty of ambition with an early curling shot which drifted fractionally wide.
Top scorer Stevie Crawford then missed a terrific opportunity to add to the four goals he had already claimed against Dundee this season when he blasted over the top after beating the offside trap.
Dundee's first attack was rewarded with what proved to be the winning goal although they could hardly take much of the credit as Nicholson deflected a harmless looking cross into his own net.
The visitors were briefly inspired with Fabian Caballero looking very dangerous but Dunfermline soon reasserted their control of the midfield with Crawford being denied by a fine defensive block by Lee Wilkie.
Dunfermline won three corners in a row as they piled on the pressure before half time and Lee Bullen was unfortunate to see two headers deflected away to safety.
It remained one-way traffic for most of the second period and Craig Brewster wasted Dunfermline's best chance midway through the half when he headed wide from six yards.
The arrival of substitute Nacho Novo gave the Dark Blues an extra cutting edge and home keeper Derek Stillie did superbly to prevent Gavin Rae making it 2-0 with 12 minutes left.
As Dunfermline went for broke in the dying minutes Stillie had to make two more top-class saves to deny Novo and Georgi Nemsadze.