Lewis Hamilton took aim at Formula One champion Sebastian Vettel's run of five consecutive pole positions Friday after topping practice for the Korean Grand Prix. In cold, wet conditions at Yeongam, Hamilton shrugged off a poor run of form with a best time of one minute and 50.828 seconds to outpace McLaren team-mate Jenson Button by 0.104 seconds. Vettel, 24, who last week was crowned Formula One's youngest ever back-to-back champion, was third fastest in his Red Bull car, ahead of Ferrari's Fernando Alonso in fourth. Hamilton finished fifth last week in Suzuka, underlining a difficult few months in which he is winless since July. But the 2008 champion said Vettel would be in his sights during qualifying on Saturday, where the German will be aiming for his 13th pole position in 16 grands prix this season. "It would be great to get him here tomorrow. Again, on a Friday we don't know what they are doing so today doesn't mean anything. But I think we are quick. I think our car was good," Hamilton said. "Jenson showed in the last race that we can be very, very competitive, so I have no doubt that we will be out to challenge them. "Whether or not we can outdo them in qualifying, which has not been done all year, will be interesting." The McLaren pair were 1.7 seconds clear of the rest in a daunting demonstration of their potential in the difficult conditions. Vettel, who can help Red Bull seal the constructors' title this weekend, admitted he was concerned over possible tyre-wear problems as he seeks his 10th win of the season. "Maybe it turns out to be better than expected -- or worse. It is quite a tough track on tyres. I think even with long straights, there is hardly any rest after that. So it's not that easy," said the German. "Everything we learned today is not worth a lot for the next two days but the car feels all right so that is most important." Several drivers struggled, but the most extraordinary accident came when Germany's Nico Rosberg of Mercedes collided with Jaime Alguersuari of Toro Rosso as the Spaniard rejoined from the pits. Rosberg ran wide at turn one and ran into Alguersuari?s car, causing damage to both vehicles. Alguersuari finished sixth behind Red Bull's Mark Webber, who was fifth, with Ferrari driver Felipe Massa seventh and Rosberg eighth. Seven-time champion Michael Schumacher, who had topped the times for Mercedes in the opening morning session, wound up 14th in the afternoon. But Hamilton admitted the wet conditions had made it difficult to forecast performances for the weekend, when the weather is forecast to improve. "Today is not a particularly important day and I heard the next two days are going to be much better, so today is kind of irrelevant set-up wise," he said. "Tomorrow we'll get a much better feel for where the car is at. But if it rains we are in a good position, so that's a positive." Red Bull will add the constructors' championship to Vettel's drivers' title if they maintain their 130-point lead over McLaren in Sunday's race.