By all accounts, at least Spanish ones this week, Claudio Ranieri believes Chelsea owner Roman Abramovich knows nothing about football.

The oil billionaire might well have been muttering much the same about Ranieri last night after Chelsea threw away what should have been at least a draw against the 10 men of Monaco in what turned out to be a desperately disappointing Champions League semi-final first-leg defeat.

No doubt what was to blame: the perplexing tinkering of the man who just doesn't understand the notion that if it's not broken it doesn't need fixing.

At half-time Chelsea looked to be cruising to the final, sitting on a 1-1 scoreline, dominating the play, stroking the ball around with authority. All they needed was another 45 minutes of the same.

Inexplicably, Ranieri brought on Juan Veron, who has barely played a match all season, in place of the lively Jesper Gronkjaer. It was like swapping a thoroughbred for a carthorse.

He followed that by throwing on Jimmy Floyd Hasselbaink for Mario Melchiot and Robert Huth for Scott Parker, and suddenly Chelsea's shape and demeanour resembled that of a deflated balloon.

Naive is the word that comes to mind. What you have is what you hold is the maxim employed by most managers when playing away in Europe - especially when you're facing a team of 10 men following the sending off of Andreas Zikos.

Ranieri, however, chanced his arm. He piled everything on the chance of throwing a red seven in the gambling mecca that is Monte Carlo and he came up with a black six.

On the way he almost certainly sealed his fate at Stamford Bridge.

Chelsea's form at home is by no means consistent and Monaco possess strikers in Fernando Morientes and Ludovic Giuly who are designed for the counter-attack game they will surely employ in the second leg.

And that is such a pity, especially for such as Frank Lampard, who has blossomed spectacularly this season in response to the faith Ranieri has shown in him.

The Chelsea man's appetite for work is the secret to his success. And his crunching tackles, crosses, surging runs and supreme composure were all on show in a first-half performance of true quality.

True, no one could argue when Chelsea went behind to Croatian Dado Prso's 17th minute header, his seventh in the Champions League this season.

But Hernan Crespo struck Chelsea level within five minutes after Eidur Gudjohnsen had slipped and then recovered brilliantly in the Monaco penalty box and it was the cue for Chelsea to impose their own authority.

It all looked to be going so well.

But Ranieri's tinkering was causing Chelsea as many problems as Monaco's lively forwards.

It was no surprise when Morientes put Monaco ahead again or when Shabani Nonda added the third.

Ranieri shook his head on the touchline. So, you suspect, did Abramovich in his corporate box.

Just one last throw of the dice remains at Stamford Bridge. No one last night, however, was betting on Ranieri.