The lead Chelsea hold over United at the top of the Premiership still stands at nine points, but the psychological implications of the two they have dropped may yet be more widespread. Mourinho pointed out tartly that there is not a club in any of the top leagues in Europe who hold such an advantage at this stage of the season, but the end of a run of eight wins in a row had plunged the Portuguese coach into a dark mood.
He snapped back at questions over the Premier League's inquiry into the "tapping up" of Ashley Cole and refused to discuss the injuries to Arjen Robben and Didier Drogba that now seem more significant than ever. When it came to City's display, he acknowledged the outstanding contribution of David James, but despaired at the defensive tactics of the opposition.
In October, City became the only team to beat Chelsea in the Premiership this season with a victory in east Manchester. With the achievements of Mourinho's side since then, yesterday's result was greeted with incredulity by an away support who taunted the Portuguese manager with the most inventive chant of the season. As he rose from the dug-out in his trademark grey overcoat they sang "Your coat's from Matalan".
But there was nothing cut-price about the team that Mourinho selected, with Damien Duff their chief threat in the absence of Robben. He led the way in a spell of Chelsea pressure at the end of the first half that James dealt with superbly. He saved the Irishman's near-post shot on 33 minutes and then tipped Frank Lampard's effort over the bar. William Gallas' header from a corner was scooped off the line by Paul Bosvelt.
For all their pressure, Chelsea could not prevent Shaun Wright-Phillips escaping down the left wing and beating Claude Makelele just before half- time. He picked out Robbie Fowler at the near post and, as John Terry slipped, the City striker put his header wide. But Mourinho would not accept his opponents were serious about attacking.
"It's an undeserved result in my opinion because only one team had real chances," he said. "But we couldn't score and they fought a lot, defended a lot and had a great goalkeeper. They were lucky and they got a point. Before the win we needed nine wins and a draw to win the title and now we only need nine wins."
It was not luck, however, that kept out Lampard's volley from eight yards deep into added time. Terry won a header in the area and the ball dropped nicely for his England colleague with just James to beat. He struck the ball low and hard to the goalkeeper's right, but James threw out a hand that deflected the shot away from a busy area full of Chelsea attackers.
Mourinho did not repeat the accusation he lodged against Tottenham, that their defending was no more subtle than the proverbial bus parked in front of a goal, but he was reminded by Keegan that teams would not come to Chelsea to attack. "I don't know what it is like in Portugal, but in England when you play teams like Chelsea you have to be sensible," he said. "What he [Mourinho] has to learn to do is to give credit to other teams - there are two in every game."
In defence for City, Richard Dunne and Sylvain Distin were outstanding, but they were still not as crucial as James. Before the City area was inundated with shots at the very end of the match, James kept out another stinging free-kick from Lampard after 72 minutes.
It might not be enough to earn him a place in the England team this week, but he and his City team-mates did at least give the rest of the Premiership a small clue as to how Mourinho's points-gobbling blue machine might be stopped in the future.
Chelsea (4-5-1): Cech; Ferreira, Gallas, Terry, Bridge; Gudjohnsen, Jarosik (Tiago, 56), Makelele, Lampard, Duff; Kezman (Cole, 62). Substitutes not used: Cudicini (gk), Johnson, Smertin.
Manchester City (4-4-2): James; Mills, Dunne, Distin, Thatcher; Wright- Phillips, Barton, Bosvelt, Musampa; Fowler, Sibierski (McManaman, 86).
Substitutes not used: Weaver (gk), Macken, Onuoha, Jordan.
Booked: Chelsea Makelele, Gudjohnsen; Manchester City Bosvelt.
Referee: H Webb (South Yorkshire)
Man of the match: James.
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