Lewis Hamilton says his Mercedes team has some 'homework' to tackle ahead of qualifying for the Spanish Grand Prix after enduring a troubled opening day at the Circuit de Catalunya.

The defending champion was third quickest in second free practice, Hamilton ending the day a sizeable seven tenths down on pace setting team-mate Nico Rosberg.

Though Hamilton went on to justify away the margin as being down to traffic on his soft tyre lap, he nonetheless says the W07's balance is not as sweet as it was during pre-season testing at the same venue.

Speculating that a change in the temperature, weather conditions and tyre pressures have played their part, Hamilton says he is not happy with the car's feedback regardless.

"Very hard, very inconsistent conditions today so it was hard to gauge what to do with the set up so that's what we've got to work hard to understand tonight," he said,

"It doesn't feel great this weekend, I don't know if it's the tyres or the wind. It's definitely a little bit different to what it was at testing.



"I think it's the same for everyone, I think everyone is struggling. They put more pressure in these tyres than we had in the winter so I'm sure that's not helping. It just gives us lots of homework to do, a lot of pressure on the engineers to analyse what's going on with the car and for me to do the background work and trying to figure out what I can do to make it better."