The former Formula One driver took the Paralympic gold medal Wednesday in paracycling -- a hand cycle powered by the arms -- at the Brands Hatch race track, posting a time of 24 minutes, 50.22 seconds.
The victory capped an incredible journey for the 45-year-old who almost died in a horrific accident at a 2001 CART race in Germany.
"It's an amazing feeling," a clearly exuberant Zanardi said. "I'm really, really happy for the result."
Zanardi celebrated by sliding out of his cycle and lifting it over his head with one hand and raising his other arm, fist clenched, to the sky.
It was unusual. It was on purpose.
"I'm Alex Zanardi," he said with a huge grin, his Italian accent dragging each syllable. "I always have to come up with something. I have a little bit of a big head."
Zanardi's journey to the Paralympics began at the American Memorial 500 on Sept. 15, 2001, at the Eurospeedway Lausitz in Germany -- the only American-based series to go forward on the weekend after the Sept. 11 terrorist attacks.
Zanardi, a former two-time CART champion, had had a difficult season. He started 22nd in a field of 27, but the car was responding well. He was enjoying the drive, passing one car after another, until with 13 laps to go he was in the lead.
Zanardi went into his final pit stop and the crew chief waved him off urging him to "Go, go, go!"
But as he built up speed to get back into the race, the car spun out of control and he veered onto the track. Canadian driver Alex Tagliani, traveling at close to 200 mph (320 kph), could not avoid him. The reinforced carbon fiber cone of Tagliani's car sliced through the area beside Zanardi's left front wheel and cockpit, the weakest part of the vehicle.
On the track, Dr. Terry Trammel slipped and fell as he raced to the wreckage. He thought he had fallen in oil, but it was Zanardi's blood.
The crash had severed Zanardi's right leg at the knee and his left at the thigh some five inches above the knee. The driver's lower legs had disintegrated like those of land mine victims, said Dr. Steve Olvey, director of medical affairs for CART at the time. He had lost 70 percent of his blood, his pelvis was fractured in five places and he had a lacerated liver.
But Zanardi was alive.
At the hospital, Zanardi's wife, Daniela, told him he had lost his legs. But that was only part of the problem. He had been in a coma for three days, his heart had stopped at least once, and he was alive only because of the medical response to his injuries.
Much work for his recovery lay ahead.
NASCAR driver Max Papis, who has known Zanardi since they were kids in Italy, recalled visiting his friend in the hospital, where Zanardi glanced at Papis' new shoes.
"He said to 'Look at the positive side of this. For a long time I will not have to spend money buying those,' " Papis said.
Pushing the limits, he began to walk again only months after the accident. Always tinkering, Zanardi used technology and his experience from working with elite race cars to forge a new life -- to adapt to his new circumstances, to learn how to use prosthetic legs.
"You don't know how many times I fell just taking ridiculous small steps," he told the BBC. "It was bloody hard."
Two years after the accident, he returned to Lausitz to finish the 13 laps, and later began racing specially modified touring cars. But he had many other races to run. Pity didn't occur to him.
"He's a lion," said his former teammate, Jimmy Vasser. "He just never gave up."
Zanardi thought of it as part of his destiny, just something that happened to him, said Chip Ganassi, who owns the team that Zanardi once raced for.
"That was like a speed bump for him," Ganassi said.
Zanardi took up paracycling to stay in shape. A hand cycle is powered by the arms and features two coasting rear wheels and one steerable front wheel. In 2007, he was invited to attend the pasta party at the New York City marathon that was thrown by his sponsor, Barilla. He decided that if he was going, he should take part. At the race, he finished fourth. By 2011, he was first.
On Wednesday, he defeated one of the best in the world -- American Oscar "Oz" Sanchez, who won a gold medal in the time trial at the 2008 Paralympics in Beijing and a bronze medal in the road race. Sanchez took the bronze in London with a time of 25 minutes, 35.36 seconds.
Norbert Mossandl of Germany won the silver in London with a time of 25 minutes, 17.40 seconds.
Zanardi knew the Brands Hatch course north of London would be tough -- he once drove it in a race car. To make things worse, he had a bad crash with his favorite bike a few weeks ago -- a picture on his Twitter feed showed a crumpled vehicle, its front wheel askew.
But by Wednesday, all that was forgotten. He said Vasser had called him Tuesday night and promised him a car for the Indianapolis 500 -- if he won the gold.
"I'll have to call him back tonight and say 'Jimmy. I got the gold medal!' ... How about the car?"
Copyright 2012 by The Associated Press