SHANGHAI, China - Lewis Hamilton went from sick to quick at the 2013 Chinese F1 Grand Prix on Friday only to find his tyres were falling apart.The two free practice sessions was the season debut for Pirelli's quick-wearing soft tyres and, while Ferrari's Felipe Massa and Lotus found them to their liking, Hamilton, well, didn't.MERC ON TOP"The worst I've experienced," he said after returning from a sick break suffering from "an allergy". "There were bits flying off all over the place - didn't last long. It (the soft) doesn't feel like the right tyre for this circuit. I did a couple of laps and the tyre disintegrated."It was quite unusual."Mercedes was 1-2 at the top of the time sheets, 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 here in Shanghai, fourth-fastest in the afternoon and Hamilton seventh, Massa was fastest.Hamilton said he 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."THREE STOPS?Pirelli motorsport director Paul Hembery said degradation had been in line with expectations on the medium tyre but not the soft, with big differences between the two."We'd expect the soft tyre to last 11 to 12 laps in the race and the medium tyre 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." Stay with Wheels24 for the 2013 Formula 1 season – fresh reports every day.