Formula One's leading drivers have complained bitterly that a new hard Pirelli tyre was 'a disaster' that left them struggling for pace in practice for Sunday's Spanish Grand Prix.
Pirelli, who succeeded Bridgestone as the sport's sole supplier this year, have introduced the new tyre at the Circuit de Catalunya, hoping to create more strategic opportunities -- adding pit stops -- for the teams.
But the drivers were on average two seconds per lap slower with the new tyres fitted -- and left the Italian manufacturer in no doubt about their feelings.
Lewis Hamilton of McLaren labelled the tyre 'a disaster', and suggested that most teams would avoid using them.
He said: "The super-hard tyre is a disaster, so that wasn't nice to drive. "There was a two seconds difference -- and they don't last that long.
"I think we are about two and a half seconds off the pace with that tyre. Then we switch to the normal soft and it's fantastic. I think you will see most people with that tyre during the weekend."
His Mclaren team-mate and fellow Briton Jenson Button admitted that he would not want to use the new tyre for any longer than required.
"It's hard, seriously hard - and at the moment we're struggling on it, I don't think you'd want to run more than one stint on it," said Button.
Double world champion Fernando Alonso of Ferrari said the tyres would be useless in Saturday's qualifying session.
"It's difficult to think about going in Q1 with the hard tyre, so I think 95 per cent of the people will try to use one soft unfortunately in Q1. We'll see if anyone takes the risk."
Pace-setting Australian Mark Webber, who topped Friday's practice times for Red Bull, also struggled.
"We didn't get the performance out of those that we would have liked," he said.
Pirelli said the new tyre would create an extra technical challenge that may take time for the teams to adjust to - if they use them.
"It is slow. It has less grip. I don't deny that," said Pirelli spokesman Paul Hembery.
"I can imagine that it has changed the balance of the car, I can appreciate that, so it is an extra technical challenge and that is something that we will get through in our debrief tonight."
He added that the drivers should have complained about them when they tested them instead of waiting until a race meeting.
"I can understand that it is different, very different, but why didn't they say those comments when they tested them in Malaysia or in Istanbul? We didn't have those comments - maybe they didn't test them correctly, didn't take it seriously enough."