Mark Hughes' Spanish GP form guide

Michael Schumacher has unsurprisingly been pressed further this weekend on his feelings about the Pirelli tyres that he was so critical of after Bahrain. Well, around Barcelona they continue to mystify the best engineering brains in Formula 1. Whether that's good or bad depends upon your viewpoint, for they are certainly contributing unpredictability, and that continued on Friday.

With all those engineering teams desperate to assess in competition the effectiveness of the upgrades made during the recent Mugello tests, the baffling behaviour of how the track and tyres seemed to be interacting made that difficult to judge. Unclouded skies had the track temperature at 32 degrees C already in free practice 1 - when teams were generally finding lots of understeer on the hard compound, against expectations - and a whopping 42C in the second session. This only increased understeer, particularly on the soft tyre.

But within that, a picture did begin to emerge from the Fan Vision laptime screens - one in which McLaren and Red Bull vied as fastest qualifiers, with Lotus looking comfortably the fastest racers. The Mercedes looked somewhere between the front and Lotus over one lap, but the slowest of the lead four teams over lots of them. The revised Ferraris appear still to be struggling for ultimate pace, looking set to fight for a place in Q3 with the likes of Sauber and Force India.

Jenson Button went out in the afternoon, complaining of incredible understeer, even after dialling it out of the car in the first session. As the track grip ramps up from both the heating and cleaning up of its surface, the car's grip increases both front and rear - but with the rear tyres being bigger the effect is greater, thereby increasing understeer. But this was beyond even that and Button was straight back in just one lap into his first afternoon run for more front wing. Upon rejoining, he reported the balance being at least as bad - and he returned again for a huge three-and-a-half turns of yet more front wing. That elusive front-end grip magically appeared - to the extent that Button was able to nail the fastest time of the day, by a significant margin.

His team-mate Lewis Hamilton, meanwhile, struggled in a blur of locked fronts as he tried for a qualifying time, but was consistently quick in the later race runs. Sebastian Vettel's Red Bull emerged as the closest one-lap threat to the McLaren - and by comparison the other usual frontrunners Mercedes and Lotus were left gasping somewhat.

Lotus seems to have the best race pace, but will its drivers qualify well enough? © XPB

But switch to race simulation and the picture changes entirely. With the usual provisos about comparative fuel loads, the Lotus pair Kimi Raikkonen and Romain Grosjean were each brilliantly quick for lap after lap - even on the soft tyres, dipping in to the 1m29s when the Red Bulls and McLarens were in the mid to high 1m30s and the Mercedes in the mid 1m31s on equivalent tyres.

The apparent inability of the Lotus to find the last couple of tenths of raw pace over one lap and its great potential race pace may be two different facets of the same underlying characteristic. Either by chance, design or set-up choices, the Lotus E20 is the only car that seems always to be quick in race trim and that does not fall in and out of the narrow little window of tyre performance. But it cannot quite summon a pole challenge either. The question may well be if the track position penalty of this trait can be overcome by the pace on Sunday at a track where traditionally passing has been difficult.

DRS should come to the team's rescue in this regard. In Bahrain, the new tyre benefit for Raikkonen of not getting into Q3 was ultimately not quite enough to overcome the track position penalty. But getting through to Q2, qualifying on maybe the third row, perhaps using just one set of softs? Will that prove to be the happy middle ground for either Raikkonen or Grosjean? Their pace is remarkably closely-matched and it's by no means a given that it will be Raikkonen who stars and not his team-mate.

Their biggest challenge to getting on terms with McLaren and Red Bull might feasibly be the Mercedes, which just may have the pace to out-qualify the Lotus but looks likely then to hold it up and which has its double-DRS to help its defence.

Meanwhile, the McLaren and Red Bull appear to be well-matched in race trim, both able to do competitive stint lengths at good pace on the softs and both not that much slower on the hards. Button's pace on the hards appeared to hold up slightly better than Vettel's - but Hamilton looked faster than either on those tyres.

But still not as fast as the Lotuses. This could be fascinating.