Michael Schumacher has admitted that he thought it would be possible to return to the top of the F1 tree within two years of coming out of retirement.

The German headed into what became a three-year sabbatical with seven world championship titles under his belt, and returned confident that he could add an eighth after teaming up with the Mercedes team that had already shocked the F1 world by taking Jenson Button to the 2009 crown under the guise of Brawn GP. Instead, the first two years of his return saw him scrape into the top ten overall, while the current campaign sees the 43-year old languishing down in 14th overall, sandwiched between Paul di Resta and Pastor Maldonado.

"I thought that two years was sufficient time to take the title," Schumacher told RTL, "It was a team that had just won the world championship, and was now a big name as Mercedes. I thought that, if we put two and two together, we would drive it forward towards that end. But it did not succeed."

While his decision to quit at the end of the 2006 campaign came on the back of a run to second place in the championship, the three years with Mercedes have seen Schumacher reach the podium just once, in an incident-filled European Grand Prix earlier this year, and have been punctuated by both mechanical unreliability and uncharacteristic mistakes from the veteran - which he says he thought about reflecting at the announcement of his second retirement.

"At the press conference in Suzuka, I wanted to come with a white cane as a nod to all the questions of whether I needed glasses, was blind at night and so on," he laughed.

This time around, the German insists that Brazilian Grand Prix race at Interlagos will be 'just another race' rather than a potential title decider.

"It would be a special race, if it would go in my favour," he admitted, eyeing a 92nd and final F1 success.