What got into Claudio Ranieri? Why, as someone put it, did he come over all Kevin Keegan? By introducing a third forward, Jimmy Floyd Hasselbaink, as a substitute when Chelsea were already performing well against Monaco in the semi-final first leg he unbalanced the team to such an extent that it may now fall out of the Champions League.

A 1-1 score at the interval decayed to a 3-1 defeat, even though the French side had only 10 players following the unjust red card for Andreas Zikos in the 53rd minute.

Ranieri's frank acceptance of blame for the result was so disarming that one almost forgot how incomplete it was as an explanation.

He said he wanted the extra attacker to prey on opponents who were a man short. It could have worked if Hasselbaink had not missed with an easy header to put Chelsea ahead moments before Fernando Morientes gave Monaco the lead instead, but the real mystery rests with Ranieri's wish to adopt a risky strategy at all.

Before half-time the imposing Frank Lampard and others were making Didier Deschamps' team look flimsy. By continuing exactly as they were, Chelsea might easily have killed off the tie with a wholly conventional win. Ranieri, too, must have appreciated the possible pitfalls in a trio of centre forwards.

They did indeed tend to bunch in the middle, cluttering Chelsea's attacking. In the whole of the English Premiership Ranieri is just about the last manager one would have predicted to be so gauche. His zany turn of speech, after all, is frequently offered as compensation for the old-fashioned Serie A conservatism that commonly characterises his work.

The staidness of his Chelsea is actually one of the grievances held by employers who are virtually sure to sack him in the summer. A club that has emphasised his vulnerability ever more heavily as the months have rolled by since Roman Abramovich's takeover may have been punished in the Stade Louis II for all the pressure they have heaped on him.

Shunning his natural instincts, Ranieri lunged for the prize on Tuesday. Although he knows that the club will ditch him, he could at least create the maximum embarrassment for the Chelsea leadership and the greatest fillip for his own reputation by winning the Champions League. The manager was in an ill-considered haste to polish off a Monaco side that cannot be taken so lightly.

Ranieri's perceptions were warped by the strain under which he lives. The unease of the Chelsea fans soon intensified. With their team in control any substitution at all for the start of the second half would have made them quizzical. It could have been pleasant to see Juan Sebastian Veron replace Jesper Gronkjaer but not under the present circumstances.

Monaco may have been concerned by the advent of the vastly gifted Argentinian but they quickly saw how diminished he is after 33 minutes of action in five months as he recovers gingerly from back surgery.

The wilful weakening of the line-up proceeded. Mario Melchiot has his flaws but removing a right back is like aiming a sledgehammer at the foundations.

The edifice cracked, as perhaps did the nerve of the unfortunate and inexperienced Marco Ambrosio. Despite being 30, the goalkeeper has made fewer than 50 first-team appearances in his career and has borne a worried air ever since injury trouble at Chelsea propelled him into football at a rarefied level. He ought to have kept out Shabani Nonda's effort for the third goal that has so demoralised Chelsea.

Once again the club has been incapable of consolidating. They have not won in four matches since what should have been the cathartic Champions League quarter-final victory over Arsenal. It is a reworking of the pattern that had them beating Manchester United in the Premiership in November and then gathering a meagre four points from the next four fixtures.

Everything flickers at Chelsea and the club has to hope that the second leg coincides with one of the periodic flashes of self-belief.

Claude Makelele, whose play-acting secured Zikos's sending off, will be suspended and so too should be Marcel Desailly after he was charged yesterday with improper conduct.

UEFA's control and disciplinary body will today review video evidence of the incident, missed by referee Urs Meier, in which the captain elbowed Morientes in the face. Any ban for violent conduct would probably cover the final as well, if Chelsea get there.

European football's governing body confirmed in a statement yesterday that "the control and disciplinary body has instigated disciplinary proceedings against Chelsea defender Marcel Desailly for improper conduct."

A UEFA spokesman added: "The control and disciplinary body will deal with this case. They will look at all the evidence, including from television."

Meier's official report will also be considered, as well as UEFA's own match delegate, before they make their final decision.

Yet an appearance for Ranieri's men in Gelsenkirchen cannot be discounted. The principal difficulty could lie in preventing a Monaco team inspired by Ludovic Giuly from scoring in the return match on May 5th.

Chelsea should be capable of goals with Damien Duff recovered from illness, and Veron, too, would be a help so long as he is in top condition.

If the team does fail to go through, Ranieri and his squad will long brood on their misuse of the momentum that a victory at Highbury seemed to have given them.