Juan Pablo Montoya was fastest in both free practice sessions as the United States Grand Prix meeting swung into action at Indianapolis. The Colombian lapped in 1m 11.118s this afternoon to outpace team-mate Kimi Räikkönen, winner of last weekend’s Canadian GP, by just 0.110s.

Of the other leading Michelin runners, Nick Heidfeld was fifth on aggregate, ahead of David Coulthard, Ricardo Zonta, Pedro de la Rosa, Scott Speed, world championship leader Fernando Alonso, Jarno Trulli and Giancarlo Fisichella.

Unbeaten so far this season, Michelin will be shooting for its 91st Formula One pole position tomorrow – and its 84th victory on Sunday.

Pierre Dupasquier, Michelin motorsport director: "Irrespective of the various fuel loads teams have been running today, I am satisfied with the way our partners and us have performed. Michelin has achieved very good results with its two available tyre compounds, but it is too soon to know whether both will be used on Sunday.

The track has evolved since this morning, as the F1 cars and Infiniti Pro Series runners have laid down more rubber, but parts of it remain extremely abrasive – particularly the recently- resurfaced banked section and pit straight, which are common to both the road course and the oval. Even so, I am confident our partners will be in good shape.

"As far as today’s on-track incidents are concerned, it is clear that two Toyotas have suffered of rear left problem. No cause as so far been definitely established and we are continuing our investigations. We are pleased to note neither driver suffered any major injuries. There were 17 Michelin cars on the circuit today and we did not have any widespread problems. Our engineers will continue to work very closely with those of Toyota while the matter is investigated."