Sir Alex Ferguson admits Manchester United have handed initiative back to Manchester City and concedes that a derby duel next Monday will be crucial in the Premier League title race.
The Red Devils offered their local rivals hope in the race for the top-flight crown as they were held 4-4 by Everton in dramatic fashion on Sunday.
The Red Devils found themselves two goals to the good on two occasions at Old Trafford, but suffered a late lapse in concentration to allow two points to slip through their grasp.
The destination of the title could now rest on a meeting between United and City at the Etihad Stadium on 30th April, with Ferguson fully aware of how important that fixture has become.
"We have given them initiative, there is no doubt about that," he told Sky Sports.
"It makes the game at the Etihad a real decider. We have made it hard for ourselves, as we normally do, but we will go there knowing that we are capable of getting a result.
"We need to get a result now at the Etihad and there is no reason why we can't do that. There has been an expectancy from City that this could be their decider, but it is our decider too.
"There will be a reaction. It's big a game next Monday against City. It is always a derby game of the highest proportions and this won't be any different."
Asked if next Monday's game would be the biggest Manchester derby of his career, Ferguson added: "Yes, it definitely is."
Ferguson admits United let themselves down defensively against Everton, with untimely errors costing them dear.
He said: "I thought it was an absolute give-away. We just had to see the game out. Some of our football was fantastic, some of the goals we scored were great goals. To give away four goals at Old Trafford, in a home game, we can't believe it.
"It was defensive lapses. I think their goals were soft. We have created goals by really good football, but I think they got their goals easy."
Who will win the Barclays Premier League?