Fernando Alonso, desperate to get his Formula One championship bid back on track, signalled his intentions to start with this weekend's Canadian Grand Prix by setting the fastest lap in practice on Friday. The Spaniard posted the day's fastest overall time when he lapped the Circuit Gilles Villeneuve in one minute 14.818 seconds during the 90-minute afternoon session.

Briton Lewis Hamilton, a three-time winner at the Montreal street circuit, was second fastest overall in his Mercedes, just 0.012 behind Alonso's Ferrari. Frenchman Romain Grosjean was third quickest for Lotus, while his Finnish teammate Kimi Raikkonen, currently second in the championship standings, was 11th.

Australia's Mark Webber was fourth for Red Bull while his teammate, triple world champion Sebastian Vettel, could only manage seventh best and was expecting a close race. "It felt pretty good. It's always difficult to know what other people are doing, but all in all it was a good run," Vettel told reporters. "Mercedes was very quick, Ferrari looked very competitive in both long and short runs, so I think those will be the main two rivals. But never forget the Lotus. They can be a surprise in the race by going further than everyone else.

" Britain's Paul Di Resta was the surprise leader for Force India after the morning session, which began in light rain with puddles of water still on the track.

But he tumbled down the timesheets to 13th place in the afternoon session, when he had an electrical problem and all the cars went much quicker after the track had dried and they switched to softer tyres. Despite two wins and a second-place finish from the previous six races this season, Alonso has slipped back to third place in the standings, 29 points behind Vettel after finishing seventh at the most recent race in Monaco.

The Spaniard has made no secret of the fact he believes he needs to finish in front of Germany's Vettel this weekend to start eating into his lead. "We can expect a very complicated weekend, because the weather is due to remain changeable right up to Sunday and judging the grip level will be difficult, both in qualifying and in the race," said Alonso.

"It was an untypical Friday, affected by the extremely changeable weather. We didn't manage to complete our programme because the track was wet in the morning and so only tomorrow will we find out if the updates we tested here produce a real performance evolution." Hamilton said he was happy enough by his car's performance but said his chances of winning would be better if the rain stayed away.

"The car felt pretty good today and I tried a couple of different things over the two sessions which made me feel a little more comfortable so that's positive," he said. "Hopefully it will be dry for qualifying tomorrow and we can have a strong day." There were no major incidents in either session although Venezuela's Pastor Maldonado hit a wall in the morning when the track was slippery and wet, breaking the front wing of his Williams.

The drivers will have a third practice session on Saturday morning before official qualifying gets underway later that day. Jenson Button, a winner in Canada two years ago, was second fastest in the morning then ninth in the afternoon after his McLaren experienced gearbox problems.

"We needed the car to be reliable and it wasn't today," said the Englishman. "But there is a lot info to look at on both cars and they were running very different set-ups and downforce levels, so at least we got some information."