Derby's Jim Smith, who first donned the player-manager's mantle at Boston United some three decades before Vialli, did not allow his side's late equaliser to tarnish a positive impression of the resilience the Italian has instilled during 10 months in charge at Stamford Bridge.
Smith's view is that the title tends to go not to the most talented or exciting team, but to the one who make themselves hardest to beat. Chelsea's run of 15 unbeaten Premiership games since the first-day flop at Coventry - contrasting neatly with 15 League defeats last season - has convinced him that their soft underbelly is now a tight six-pack.
"They are very serious contenders," said Smith. "I think it will go to the wire between Chelsea, United, Arsenal and Aston Villa. Arsenal have that ability to dig in and get results, and Villa have added players since they beat us.
"The difference with Chelsea is that they are so good going forward, a bit like United. We felt that we could cause them problems if we got enough balls into their box, but it's not that easy because you can't get the ball off them."
Derby, however, managed to fulfil their manager's brief in stoppage time. The first triple substitution of his career paid off when one replacement, Kevin Harper, crossed for another, Dean Sturridge, to equalise and negate Chelsea's second-half ascendancy.
The switches made by Smith were born of necessity, if not desperation. Vialli, like Ruud Gullit before him, routinely tinkers with his line-up simply to keep players fresh, and indeed made six changes to the side who had overcome Villa three days earlier. Hindsight may show it to be a case of cutting off your nose to spite your face.
Tore Andre Flo, for instance, is by no means certain to start at Old Trafford on Wednesday. Vialli's track record suggests he may pair himself with Gianfranco Zola and bring the Norwegian off the bench. After Flo's classic demonstration of centre-forward play against Derby, including a goal which combined deftness and bravery, such a decision would be music to the ears of Jaap Stam and company.
Two players who will almost certainly return are Marcel Desailly and Albert Ferrer, in place of Michael Duberry and Bernard Lambourde, respectively. Ensuring that your first-choice centre-backs are in the right condition to face Messrs Yorke and Cole is all very well, but it could be argued that their absence needlessly exposed Chelsea at the critical moment.
For all the importance of squad depth to cover for injuries and suspensions, history shows that the champions field their strongest XI whenever possible. Villa, to quote an admittedly freakish precedent, used only 14 players in 1980-81. Liverpool regularly took the premier prize under Bill Shankly and Bob Paisley with a team in which nine or 10 men were fixtures.
Chelsea have already used 21 players, one more than in the entire 42- match programme in 1954-55, their only championship campaign. Having said that, Jody Morris made a strong case for retention ahead of Roberto Di Matteo with a first starting appearance full of industry and invention. His exquisite pass set up Flo's riposte to Horacio Carbonari's opener, and Gustavo Poyet's drive promptly put the visitors within reach of the summit.
That they were unable to plant the blue flag there for the first time in nine years was a tribute to Derby's own collective resolve - which should ensure that they finish closer to the European places than to the danger zone - and to an inspired example of team rotation by Vialli's veteran adversary.
Goals: Carbonari (26) 1-0; Flo (54) 1-1; Poyet (58) 1-2; Sturridge (90) 2-2.
Derby County (3-5-1-1): Poom; Prior, Carbonari (Sturridge, 78), Laursen; Delap, Bohinen (Schnoor, 78), Powell, Eranio, Dorigo; Baiano (Harper, 78); Wanchope. Substitutes not used: Elliott, Hoult (gk).
Chelsea (3-5-2): De Goey; Lambourde, Beboeuf, Duberry; Goldbaek (Petrescu, h-t), Morris (Babayaro, 88), Poyet, Wise, Le Saux; Flo, Zola (Nicholls, 88). Substitutes not used: Di Matteo, Hitchcock (gk).
Referee: P Jones (Loughborough).
Bookings: Derby: Powell, Carbonari, Wanchope. Chelsea: Flo.
Man of the match: Flo.
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