Saturday's row? Blame it on lactic acid and bad blood. A few years ago, players would not emerge for their warm-down until as late as 20 minutes after the match. Now it is more like five, as managers - especially ones with important Champions League matches coming up - realise that a post-match stretch is more effective while weary muscles are warm.

At the final whistle, players go inside for a quick post-match debriefing, have a bite to eat and, before they have had time to digest their banana, let alone digest what happened during the match, they are back on the pitch.

Sometimes, they return so quickly that not even all the fans have left the stadium, which can provoke flashpoints.

In January, Liverpool claimed that Jamie Carragher was spat at and had beer thrown at him as he was warming down after the FA Cup draw with Luton Town at Kenilworth Road, which caused a confrontation between the defender and spectators.

When players are tired, frustrated and angry, have just lost a crucial match in a controversial way and are probably still complaining about it, it would take only something small to trigger an incident. Things that would be laughed off or ignored after a win become an excuse in defeat to vent some fury.

So the trouble at Stamford Bridge was sparked by a combination of the importance of the match, the way it panned out for Manchester United and how soon the warm-down took place. Who knows, maybe even amazement that a 12.45pm kick off was a really exciting game. Even Avram Grant, the Chelsea first-team coach, looked animated.

And add this to the mix: the best teams are the worst losers. Just take the league's best managers in the past few years: Sir Alex Ferguson, José Mourinho, Arsène Wenger. All big winners, all bad losers - and their teams reflect their managers' personalities.

There are plenty of examples: Rio Ferdinand kicking a wall on Saturday - and think back to the spats between United and Arsenal, on the pitch and off; the pizza at Old Trafford, the antics between Ruud van Nistelrooy and Martin Keown when the striker missed a penalty a couple of years ago. If Rafael Benítez, the Liverpool manager, ranted and raved a bit more after defeats, his club may not win any more admirers, but perhaps they would be more successful.