No testing has hurt Formula One comeback - Schumacher

It is the nature of modern F1 that has contributed to Michael Schumacher's difficult comeback so far, the seven time world champion has insisted.

Two years ago now, the famous German - who will turn 43 next month - announced his return after a three-year break to the sport he once dominated.

Michael Schumacher, Mercedes GP

Photo by: xpb.cc

Having scooped an incredible 91 wins and 154 podiums in his first career, Schumacher is yet to return to the rostrum after one of his 38 Grands Prix with Mercedes since 2010.

It has been speculated that Schumacher is now either too old to perform to his old standards, or no longer fully focused and determined.

"Some have questioned whether my mood has changed. It would be nice if outsiders didn't make guesses without knowing," he said in an interview with Italy's Corriere della Sera.

Schumacher insisted that F1 is a "major challenge", both for himself and for Mercedes-Benz, who are still building up their Brackley based works team.

He acknowledged: "I thought that I might be (on the podium) at least a couple of times. Together we have to work hard to improve performance but we are not afraid of that.

"In F1 there are no magic wands.

"In the past we did a lot of testing," said the former Ferrari driver. "Today not, so I have had some problems with the tyres. I have not learned how to interpret them correctly.

"Previously I came to the race weekend knowing what was coming. Now the tests don't come until Friday and I am still getting used to this system."

Schumacher's existing contract runs out at the end of 2012.

"Will I be here in 2013? There is no hurry yet to think about it," he insisted.