Four-time F1 World Champion Alain Prost has accused his fellow grand prix legend Michael Schumacher of 'a lack of humility' in his rather overblown boast that he was returning to the grid bidding to clinch an incredible eighth crown in 2010 - as Flavio Briatore warned the German that if he stays put into 2011, it will only be 'the same story' again.

Prost himself has first-hand experience of rejoining the fray following some time away, going on to sensationally claim a fourth drivers' trophy at the highest level with Williams-Renault back in 1993, having sat out the 1992 campaign on sabbatical. Whilst the Frenchman had only been absent for a year, however, for 'Schumi' it was three full seasons since his original 'retirement' from active competition at the end of 2006, and at 41 he is some three years older than 'Le Professeur' was, too.

That being the case, the man whose erstwhile record of 51 grand prix victories Schumacher fairly tore apart has suggested that the Kerpen native's stated goal was 'too high and unrealistic' upon his comeback with Mercedes Grand Prix in F1 2010 - particularly in the light of how he has been routinely and comfortably outpaced, out-qualified and outscored by young team-mate and compatriot Nico Rosberg and has not had so much as a sniff of the podium, let alone the victories or title challenge he had promised.

"He should have said he was coming back to help Rosberg, or Mercedes in its first year, or his friend Ross Brawn - it would have been easier for him," the 55-year-old told French sports newspaper L'?quipe. "It may have been a lack of humility, but I think he saw himself as more powerful than that.

"For me, it's just a question of age. I think the tyres are just an excuse, because Schumacher always adapted to any sort of car - it was his great strength. It's just not possible to return to the top after being away for three years at that age. It's a matter of physiology."

Those sentiments are broadly corroborated by Schumacher's former team principal Briatore, the man who helped to guide the 91-time grand prix-winner to the first two of his seven title triumphs at Benetton in 1994 and 1995, and who is eyeing a paddock return of his own in 2013 in a commercial capacity.

"We know the Schumacher of Benetton and Ferrari," the Italian told the Times of India. "We know him as a super champion. It was not the right decision on his part to make a comeback. If he continues next year, it will be the same story."