Formula 1 title contender Lewis Hamilton says the grip levels he experienced during Friday practice for the Hungarian Grand Prix were among the worst he could remember.
The 2008 world champion topped both Friday sessions on another sweltering day at the Hungaroring, where track temperatures reached 56C.
Hamilton ended the day over two tenths of a second clear of Mercedes team-mate and championship leader Nico Rosberg, but bemoaned the lack of grip he could feel from the Pirelli tyres.
Many drivers complained of a lack of grip from the medium compound in the morning session, and Hamilton said he was not sure if the tyres or the track itself was to blame.
"The tyres feel really bad this weekend," Hamilton said.
"I can't remember them feeling so poor grip wise for some time, but it might be the track, I don't know.
"Today we had to drive so slow to look after the tyres - it feels like we have to slow down too much now, to the point where it's kind of boring.
"[But] I think the grip level will get better tomorrow."
Pirelli boss Paul Hembery said F1 teams always struggle with their cars on the first day of running in Hungary, because of how much circuit conditions evolve.
"It's hard here for teams to find a balance for the whole lap," Hembery said.
"It starts off Friday they're not happy and usually by Saturday they've found a good balance.
"There's a 1.6-1.8s gap between the two compounds, which we expected, and the medium tyre on this type of surface will just struggle to gain decent grip.
"We're slightly surprised the softer tyre was degrading so little - it did well over 20 laps with minor levels.
"We debated coming here with the super-soft, but there are a lot of loaded corners and we felt it would have been far too aggressive in these temperatures."