Wednesday 5 August at 15:59 : Aug.5 (GMM) A lingering neck injury could prevent Michael Schumacher from making his sensational return to formula one this season

The seven time world champion hurt his neck while testing a German Superbike in Spain in February, and Ferrari cautioned last Wednesday that Schumacher's return will only be confirmed after a round of intense training and medical checks

Schumacher, 40, was hospitalised after the Cartagena fall, and it was 100 days before he returned to the saddle of a racing bike

When he attended a F1 test in early March, moreover, observers said the German was not able to move his neck freely

After his nearly 70 laps in a 2007 Ferrari last Friday, Schumacher said on his official website michael-schumacher.de this week that "my neck pinches a bit"

"We have to get a grip on that as health has priority -- that's the clear arrangement made with Ferrari and, by the way, with my wife, too," he added

Now, his spokeswoman Sabine Kehm has told German television ZDF: "It is not quite certain yet that his neck will hold and the comeback can be started," adding that whether Schumacher will race at Valencia "depends on medical investigations"

His manager Willi Weber said those checks will take place next week