The Chelsea manager was left visibly stunned by his own team's rapid fall from their San Siro high and acknowledged that he had a problem requiring urgent attention if Chelsea's championship challenge was not to go the same way as all the others these past 45 years.
That could mean still further strengthening of his squad of all-stars, which can only be more bad news for the less affluent likes of Derby, who are struggling, as it is, to keep up with the big spenders. However, he seemed to suggest there was more of a psychological problem than an attitude one among his players in their inability to lift themselves, particularly away from home, for the bread-and-butter stuff of the league. To the lesser trained eye, it smacked of straightforward complacency.
"Obviously I must have done something wrong," said Vialli with typical honesty, "because the way we played was not the way Chelsea Football Club must play. We've got so much quality, so many good players. I wouldn't say we didn't try, I think we tried quite hard."
The first 15 minutes may have been the problem because Chelsea were so much better than their opponents that, subconsciously, they may have taken their foot off an accelerator that had been pressed hard to the floor just three days earlier in order to hold off the high-speed challenge of Milan.
In mitigation, they were without five of those who had started against the Italian champions, and after 52 minutes they lost Frank Leboeuf because of an ankle which he had injured when equalising for Chelsea in the first half. It meant that they were without both their centre-backs, since Jes Hogh had gone off in the first half with an eye injury. Marcel Desailly was already among those missing, through suspension.
Bernard Lambourde, who came on for Hogh, never looked comfortable alongside Celestine Babayaro in the centre of the Chelsea defence. They must hope that Leboeuf recovers in time for the final, all-important Champions' League group game against Hertha Berlin at Stamford Bridge on Wednesday.
Having started the game with all the misgivings of a side who had not won at home in the league since August, Derby were still unable to believe in themselves when Deon Burton put them ahead after seven minutes with a pass which appeared to come from a Chelsea player. Their lack of conviction was well-founded since Chelsea were level two minutes later when Leboeuf worked forward to do Chris Sutton's job for him.
Bit by bit, Derby improved and by half-time they should have been two goals ahead. But, just when it looked as if they might be denied their first win in seven Premiership games, their leggy Irish midfielder Rory Delap struck twice in the last 10 minutes from outside the area.
Goals: Burton (7) 1-0; Leboeuf (9) 1-1; Delap (80) 2-1; Delap (88) 3- 1.
Derby County (4-4-2): Hoult; Carbonari, Laursen, Schnoor, Dorigo; Delap, Powell, Johnson, Eranio (Borbokis, 73); Fuertes (Morris, 81), Burton. Substitutes not used: Christie, Knight (gk).
Chelsea (4-4-2): De Goey; Ferrer, Leboeuf (Deschamps, 52), Hogh (Lambourde, 33), Babayaro; Poyet, Di Matteo, Morris, Ambrosetti (Harley, 63); Sutton, Zola. Substitutes not used: Flo, Cudicini (gk).
Referee: R Harris (Oxford).
Bookings: Derby: Schnoor, Burton, Eranio. Chelsea: Lambourde.
Man of the match: Delap.
Attendance: 28,614.Reuse content