Lewis Hamilton went from sick to quick at the Chinese Grand Prix on Friday only to find his tires were falling apart.
The two free practice sessions marked the season debut of Pirelli's quick-wearing soft tires and, while Ferrari's Felipe Massa and Lotus found them to their liking, Hamilton was of the opposite opinion.
"My tire was the worst I've ever experienced. There were bits flying off it all over the place. It didn't last long," said the Mercedes driver, who had retired to his hotel with an allergy on Thursday.
"It (the soft) doesn't feel like the right tire for this circuit. I did a couple of laps and the tire disintegrated. It was quite unusual," the 2008 Formula One champion told reporters.
Mercedes were one-two at the top of the timesheets, with Nico Rosberg leading, in a morning session that saw only the medium compound used.
The soft told a different story with Rosberg, last year's winner in Shanghai, fourth in the afternoon and Hamilton seventh while Massa was fastest.
Hamilton said he had felt a little uncomfortable in the car.
"We made a change going into free practice two with the brakes and there was a big difference, a positive step, and I'm hoping we can make some more steps like that just to make feel more comfortable in the car," he explained.
Pirelli motorsport director Paul Hembery said degradation had been in line with expectations on the medium tire but not the soft, with big differences between the two.
"We'd expect the soft tire to last between 11 to 12 laps in the race and the medium tire for about 18 laps," he added.
"This would suggest a maximum of three pit stops but it's also possible that we'll see two stops if the track keeps on evolving at this rate."