Alessandro - or Alex as the Americans inevitably re-christened him - Zanardi is a 32-year-old Italian entrusted with the task of directing the sport's most successful team out of a relative slump and into the more familiar confines of the winner's enclosure.
Williams' trust is based on Zanardi's remarkable record over the past three seasons, and on the performances of the man he effectively replaces, Jacques Villeneuve. The Canadian repaired the damage to the perception of the transatlantic raider created by Michael Andretti's ill-starred adventure, by winning the 1997 world championship.
Villeneuve's defection to the embryonic BAR camp was a severe blow to Williams. Already intent on unloading Heinz-Harald Frentzen and unable to compete for the services of Michael Schumacher or one of the other leading Formula One drivers, the team decided to follow up on a contact with Zanardi.
In his first two seasons in the Champ Car series, Zanardi had been rookie of the year, then champion. He leaves with a second title and an unparalleled record of 15 wins from 50 starts.
Williams are equally impressed with his style of driving. He is a renowned charger, a racer in the image and likeness of Villeneuve, Nigel Mansell and Keke Rosberg, men who embodied the spirit of Frank Williams and his long-time partner, Patrick Head.
Zanardi also brings experience, albeit experience garnered from another arena, driving heavier, less sophisticated cars. He knows his way in racing, and that is considered a crucial attribute since the team's other recruit, Ralph Schumacher, is 23 and still learning the ropes.
Zanardi was given his first opportunity on the grand prix circuit in 1991 by Jordan, who had unearthed the gem called Michael Schumacher only to have him whisked away by Benetton.
Zanardi made nothing like the same impact as the original Schumacher but after three races with Jordan and one with Minardi in 1992, he won a full-time drive and admirers at Lotus the following year.
He earned his one, and so far only, Formula One point in Brazil and his season was cut short by a spectacular accident at Spa. Still more damaging was the demise of Lotus and their withdrawal at the end of 1994 left Zanardi in the pits without a car after 25 grands prix.
He sought employment in GT racing in 1995 before trying his luck on the American tour with Chip Ganassi's team, a move which changed his fortune and his life. He could have stayed to attempt a hat-trick of series victories, but the professional and personal lure of Formula One was too much to resist.
He is said to have signed a three-year deal worth more than pounds 10 million, time and compensation enough to carry him through what may be a difficult transitional period for the team before they launch their alliance with BMW in 2000.
"I had a thousand reasons for coming back to Formula One," Zanardi said. "I wanted to be back in Europe, to see my wife again and see my child grow up in an environment which means a lot to me and which I was missing.
"Professionally I can now express myself in a discipline which did not really provide the opportunity the first time. It was time to finish one chapter and start another. I might regret it one day, but at the moment everything is wonderful."
His perspective of wonderland has been challenged already by test sessions in the Williams, something of a culture shock for an American racing hero. "I did not expect it to feel so strange," he said. "It has changed completely and in every way. The most surprising thing is the driving position. Never before have I sat in a racing car with my feet higher than my backside. I am also used to driving much heavier cars. When I was at Lotus it was a prehistoric era, now it's space-age.
"Every lap I take in the Williams teaches me something new, which is exactly what we are here to do. The more I drive the more the fog clears from my mind. I'm here to learn and to communicate my experiences and opinions with the team. I will be eager to get back in the car after the New Year."
He and the team will be keener still to put their new car through its paces. "The team are currently third in the constructors' championship and a slight improvement will be a good enough start," Zanardi said. "Having seen the factory and the programmes that are under way, it is clear Williams are not expecting to go without success for the next couple of years. But I have no target for 1999, apart from doing my best. Everything will depend on the car."
Whatever the competitiveness of the Williams, Formula One is ready to embrace Zanardi again. Cheerful and popular in his original guise, the mature version also offers candid expression born of achievement and self-assurance. The coming months will determine whether he regrets his return.