Michael Schumacher is likely to retire for good at the end of this season after failing to beat a talented new generation of drivers since his return to Formula One, according to former team mate Johnny Herbert.
Seven-times world champion Schumacher has struggled since his comeback after three years on the sidelines in late 2009, failing to get on the podium in 23 starts and coming nowhere close to a 92nd Grand Prix victory.
"He did not return just to run in the middle order," Briton Herbert, Schumacher's team mate at Benetton in 1995, wrote in a column in Abu Dhabi's The Nation newspaper.
"His dream was to win again and make Mercedes race winners, but it has not turned out that way and I would be surprised if he chose to continue."
Herbert said age -- Schumacher is 42 -- is not a factor and that drivers like world champions Sebastian Vettel, Lewis Hamilton, Fernando Alonso as well as Schumacher's Mercedes team mate Nico Rosberg had just raised the bar.
"The simple fact is that he is no longer the best driver on the track," Herbert wrote. "Schumacher has not lost any of his skill -- the new generation of young drivers are just better than him.
"It is a case that the level required to win in F1 has gone up and he is not at that standard anymore."
Herbert said being beaten regularly by Rosberg is a "concern" for Schumacher, and that younger drivers are clearly no longer in awe of the German.
"In the past, Schumacher was able to be very forceful in races and his sheer presence would almost force cars to pull aside or back out of situations," he wrote.
"But this is no longer happening and you are seeing this with the number of incidents he has been involved in both this year and last season as well."
Schumacher finished 12th in the Turkish Grand Prix last weekend after clashing with Renault driver Vitaly Petrov and told the BBC he no longer feels "big joy" racing.
His next chance to turn things around will come on May 22 at the Spanish Grand Prix, a race he has won six times including for four years in a row from 2001 to 2004.