That, however, was then. Now, as a poacher-turned-manager, Gullit has made his old rival a pivotal member of his pot-hunting international brigade.
It was as a midfield marauder that Petrescu burst into the Steaua team at the age of 19. And that is the role he happens to be fulfilling with conspicuously consistent distinction, after spending the best part of a decade dallying between right-back, midfield and wing-back duties.
Chelsea's ultimately overwhelming dismissal of Sheffield Wednesday's nominal challenge at Hillsborough on Saturday was a collective triumph, towards which four of the seven foreign legionnaires called into action contributed goals. But it was Petrescu's perpetual scheming and probing, midway through the first half, that gave them a grip on a game they ought to have strangled even more decisively than they did.
Unlike the ponderous Wednesday defence, he even managed to dispossess Gianluca Vialli, halting his Italian colleague in mid-dribble before turning and summarily dispatching the right-foot shot which opened the scoring on the half-hour.
It was a strike, and a striking performance, that must have compounded the pain for the Wednesdayites. It was Petrescu's inability to settle into the Wednesday team, let alone into a specialist position, that prompted his departure from Hillsborough two years ago.
Glenn Hoddle signed him as a right wing-back but Gullit has unburdened him of defensive duties. "I know what his qualities are," the Chelsea manager said. "When he was a wing-back he was always best coming up on the overlap.
"Now he has somebody behind him who does all the hard work. He can give more attention to the attacking part, which I think is his strongest point.
"Of course, he has had to adapt himself. At first he was playing well one week, then not so well the next. But now he has found his rhythm."
So, it seems, has Gullit. Squad rotation is showing no sign of disturbing the pleasing pattern of Chelsea's slick-passing play.
It was difficult to argue with Ron Atkinson when the Wednesday manager suggested Chelsea probably had harder practice matches. If they lined up on the training ground with Vialli and Gianfranco Zola in attack, as they did on Saturday, the other team could rely on the forward power of Tore Andre Flo, who started on the bench at Hillsborough, and Mark Hughes, who was suspended.
Gullit's rhythm method may yet end the pregnant pause they have endured at the Bridge since Roy Bentley and Co secured Chelsea's one and only championship, back in 1955. As for the wing-clipped Owls, a pet rescue could be required - if not a Petrescu.
Goals: Petrescu (30) 0-1; Vialli (56) 0-2; Lebeouf pen (65) 0-3; Pembridge (70) 1-3; Flo (84) 1-4.
Sheffield Wednesday (4-4-2): Pressman; Nolan, Newsome, Walker, Stefanovic; Whittingham (Alexandersson, 58), Collins (Hyde, 58), Rudi, Pembridge; Booth, Di Canio (Carbone, 68). Substitutes not used: Humphreys, M Clarke (gk).
Chelsea (4-4-2): De Goey; Sinclair (S Clarke, 76), Leboeuf, Duberry, Le Saux; Petrescu, Wise, Di Matteo, Nicholls; Zola, Vialli (Flo, 65). Substitutes not used: Lambourde, Granville, Kharin (gk).
Referee: G Barber (Surrey).
Bookings: Sheffield Wednesday: Nolan. Chelsea: Sinclair.
Man of the match: Petrescu.
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