Alex Ferguson has admitted that he is still haunted by Manchester United's 6-1 loss to Manchester City at Old Trafford last month.
The defeat shocked United and the wider football world after Ferguson had dismissed his arch-rivals as "noisy neighbours".
Ferguson has admitted that the result has not gotten any easier with time.
"We've looked at that game so many times and it was suicide," Ferguson told Inside United magazine.
"We were our own worst enemy. We made a basic error of trying to win the game when we were 3-0 down, with ten men.
"It's drummed into the players to never give in but even in injury time we kept trying to attack and that left us exposed. Had we kept things simple, and not lost our heads, it could have been respectable."
Manchester United are currently five points behind Premier League leaders City.
