Manchester United have moved to a position of strength at the top of the Premier League. They will cherish their six-point lead over the team that caused them so many hardships last season but that tells only a part of the story of a match that saw Rio Ferdinand's eye split open, purportedly by a missile thrown from the crowd, and a Manchester City fan running on to the pitch to try to get to him.
Sir Alex Ferguson's team had just reminded us of their remarkable habit for scoring late, decisive goals and it ended acrimoniously. The pitch invader was wrestled to the ground but a Football Association inquiry is inevitable because of the scenes that came after Van Persie's free-kick took a slight yet crucial deflection off Samir Nasri's shin.
A team that surrendered an eight-point advantage over the final six games of last season cannot be lulled into a false sense of security, but United are entitled to reflect on a hugely satisfying day's work and their players took great care to make that point. Ferguson and Carlos Tevez, two old enemies, became embroiled in a row at the end, and Phil Jones, already booked for provoking the home crowd, seemed determined to prolong the argument.