The Dons needed an injury-time penalty from Rory Fallon to take the game into extra time as a thrilling match ended 3-3.

But after extra time failed to find a winner, it was the Fifers who kept their cool to win 4-3 on penalties with Chris Clark missing the decisive spot-kick for the Dons.

When asked if he feared his position was in danger following the defeat coupled with his side's poor start to the SPL season, the Aberdeen manager said: "I have never considered that. I have got confidence in my own ability to turn things around.

"I think Archie (Knox) and I are capable of that. I have never considered my own position at all and even after tonight I'm determined.

"If other people consider it there is nothing I can do about that - I just have to get on with my job conscientiously."

The Dons supporters have become accustomed to seeing their team crash out of cup competitions in recent seasons with East Fife joining the likes of Raith Rovers, Dundee, Dunfermline, Queen of the South and Queen's Park who have caused upsets at the expense of the Pittodrie outfit.

And Brown admitted it ranked among his worst nights in football.

He added: "I would say that was arguably the worst result of my managerial career.

"We didn't play at all. I possibly made a mistake by changing the team too much and leaving out good players from the start thinking we had enough in reserve to cope with this fixture.

"With hindsight to leave out Mawene, Milsom and Osbourne was possibly not the right thing to do.

"It just confirmed what we thought that some of the fringe players are not up to the standard that we would hope."

East Fife manager John Robertson heaped praise on his players for their heroic efforts.

He said: "I have been lucky enough to be involved in a lot of giant killing acts in the past but that was sensational.

"I thought we played super stuff in the first half and what really delighted me was the quality of the goals. I thought all three goals were absolutely magnificent and well worked.

"Aberdeen's main weakness this season has been at the back and we knew our players could get forward and hurt them.

"We told them that they had nothing to fear. They were dropping like flies in extra time with cramp but they hung in there and in the end I don't think anybody would deny that we were worthy of our victory."