Schumacher, now 40, is a seven-time world Formula 1 champion
Seven-time Formula 1 champion Michael Schumacher has abandoned his comeback with Ferrari because of a neck injury.
The 40-year-old, who retired at the end of 2006, was set to deputise for the injured Felipe Massa at the European Grand Prix in Valencia on 23 August.
"Unfortunately we did not manage to get a grip on the pain in the neck which occurred after the private F1-day in Mugello," Schumacher told his website.
Veteran Ferrari test driver Luca Badoer will now stand in for Massa.
Schumacher aggravated a neck injury he originally suffered in a bike accident in February whilst trying out a 2007 F1 car as he set about making his comeback.
But the 40-year-old German revealed: "The consequences of the injuries caused by the bike accident, fractures in the area of head and neck, unfortunately have turned out to be still too severe.
"That is why my neck cannot stand the extreme stresses caused by F1 yet. These are the clear results of the examinations we did on the course of the past two weeks and the final examination on Monday afternoon.
"As there were no improvements after the day in Mugello, I decided at short notice on Sunday to do that thorough examination on Monday."
Schumacher contacted Ferrari president Luca di Montezemolo and team boss Stefano Domenicali on Monday evening to tell them he had lost his fitness battle.
"I'm very sorry about the problem that will stop Michael returning to racing," Montezemolo said.
"His return would surely have done Formula 1 good and I'm certain we'd have seen him fighting for victory again.
Classic F1 - Chinese Grand Prix 2006
"I want to thank him in the name of Ferrari and all the fans for the attachment to the team he has shown in these circumstances."
After a decade as a test driver for the team Badoer, 38, is himself returning to racing after a long absence.
The Italian started 49 races for Scuderia Italia, Minardi and Forti between 1993 and 1999 without scoring a point.
His last competitive drive saw him qualify last and retire early from the 1999 Japanese Grand Prix.
Schumacher won five championships with Ferrari and had been working as a consultant for the Italian team before his decision to come out of retirement to stand in for Massa.
The German, who claimed his other two drivers' crowns with Benetton, has entered 250 grands prix, winning a record 91 of them.
I am disappointed to the core... I am awfully sorry for the guys of Ferrari and for all the fans which crossed fingers for me
His return was eagerly anticipated but, despite trying everything 'medically or therapeutically' possible, he has had to admit defeat.
"I am disappointed to the core," he said. "I am awfully sorry for the guys of Ferrari and for all the fans which crossed fingers for me.
"I can only repeat that I tried everything that was within my power. All I can do now is to keep my fingers crossed for the whole team for the coming races."
Brazilian Massa is recovering from the serious head injuries suffered during qualifying for the Hungarian GP.
And, while the rest of the F1 drivers were enjoying their mid-season break, Schumacher had embarked on a rigorous training regime, resulting in him losing more than six pounds in weight before calling off his return.
"It's hugely disappointing," said David Croft, Radio 5 live's F1 commentator. "The F1 world was very much looking forward to seeing Michael Schumacher locking horns with Lewis Hamilton, Jenson Button, Kimi Raikkonen and Fernando Alonso.
"But it's hardly surprising. The g-forces that your neck muscles particularly are exposed to in a modern-day F1 car can take their toll and give you severe punishment during the course of a race.
"If you are not 100% fit, there's no way you can think about driving one of these cars."
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