Schumacher threatens to retire if Ferrari fail to keep up

Michael Schumacher has given his clearest indication yet that he is considering retirement, and that further underachievement by his Ferrari team would be unacceptable and would have a crucial influence.

Just turned 37, the former multiple world champion is now the oldest driver on the grid. As he prepared to resume testing prior to the start of the Formula One season in Bahrain on 12 March, he urged his Ferrari team to make progress after his disastrous 2005 campaign in which he played second fiddle to rising talents of Fernando Alonso and Kimi Raikkonen. The Spaniard became the youngest-ever champion as Schumacher had to settle for one win and only third place overall.

He told Germany's Der Spiegel: "If we want to progress we need more staff. If I don't have the chance to win races and challenge for the title, then I don't think I'll be very keen to extend my career."

Schumacher's contract with Ferrari, believed to be worth at least $30m (£16.9m), expires at the end of 2006 and it is unclear whether he will extend it for a further two years.

In 2005, Ferrari and Bridgestone were completely outclassed by Renault, McLaren and Michelin but rule changes, in particular the return of tyre changes during races, will almost certainly help his team and tyre supplier to recover some lost ground.

Nevertheless, the improvement in performance by Renault and McLaren, together with the huge budget efforts of rising teams Toyota, Honda (née BAR) and Red Bull are also food for thought for a man who has not been used to playing a bit part since he claimed his first of seven world titles back in 1994.

"In Formula One," Schumacher said, "you cannot afford to stand still and I want to know where we're heading." His comments, which have been interpreted more as a subtle gee-up, came after he had recently tipped the team to return to its customary level of competitiveness.

Maintaining his edge despite advancing years is a challenge Schumacher would relish. But against that there are other factors to consider. Not the least of these is Alonso's scheduled switch to McLaren for 2007, and the firm belief in F1 circles that Raikkonen already has some sort of agreement with Ferrari for that season.

Even Schumacher, who has habitually liked to race with team-mates who know their place, might think twice about taking on the 26-year-old Finn head-to-head in similar equipment.