Graeme Souness believes Manchester United's late winner against Manchester City will give them a huge psychological boost over their rivals in the title race.
Wayne Rooney gave United a 2-0 advantage at the break but champions City battled back through Yaya Toure - and Pablo Zabaleta looked to have earned the hosts a point with four minutes to go.
However, there was more drama to come as Robin van Persie's stoppage time free-kick deflected in off Samir Nasri's outstretched leg to send all the points United's way and end City's two-year unbeaten run at home in the league.
The victory also moves United six points clear of their neighbours at the top of the Premier League and Souness believes the win will be worth more than just three points to Sir Alex Ferguson's side over the course of this campaign.
"Psychologically it is enormous," Souness told Sky Sports.
"Of all the teams they could have lost their home record to United was not the team they'd want to lose it to.
"City will look at that game and think they had done all the hard work. They found themselves 2-0 down and they got back into it but they've conceded a third goal which is so avoidable.
"Manchester United were rocking at one point. At 2-2 they were thinking 'oh no, not more of the same, we've been in this situation many times this season, bossing the game and then conceding'.
"But for United to come away with three points is a great result for them."
Souness was highly critical of City's French midfielder Nasri, and said the former Arsenal man should have been far braver when he was standing in the wall for Van Persie's late free-kick.
"Carlos Tevez walks away from the end of the wall and then Nasri - what are you doing, son? He's hiding," said Souness.
"Surely they've worked on that and said 'are you prepared to take a blow for the cause?' Nasri's not doing that.
"All their training, all the work they've done on the pitch goes out of the window because somebody doesn't do their job properly in the 94th minute. The worst that could happen is he gets the ball in the face."
Mario not super
Meanwhile, Jamie Redknapp was unimpressed with another City player - Mario Balotelli. After an ineffective 51 minutes the Italian was replaced by Carlos Tevez, who impressed Redknapp with his hard work for the team.
"They brought Tevez on for Balotelli and he brought enthusiasm, desire, he ran down the channels and he wanted the ball to his feet," said Redknapp.
"They became a team then because Balotellli was only worried about himself. Any Man City fan must be saying 'we're a better team without Balotelli'. It's like playing with ten men.
"Then when he came off he went down the tunnel and had the cheek not to watch his team mates. I couldn't believe it."
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