British Champ Car rookie Dan Clarke earned his first provisional pole position on Friday at Road America with an inspired late lap on a wet day in Wisconsin.

Clarke was one of only two drivers to try slick tyres during Friday's provisional session, their brave choice coming good in the closing minutes as Clarke led fellow rookie Charles Zwolsman to the chequered flag and a sweep of the front row of the overnight grid.

Poor conditions throughout the day over sprawling 4.048-mile road course looked like rendering qualifying completely wet and indeed many drivers opted to stay on wet tyres all through the session.

However Clarke and Zwolsman gambled on slicks and were able to dodge the puddles and shoot to the top of the charts right at the end of the session.

Clarke's fastest time of 1 min 55.123secs was nearly half a second faster than Zwolsman's best which, in turn was some two seconds quicker than third fastest driver Alex Tagliani, who led the list of drivers who stayed on wets throughout.

Behind Tagliani, the three remaining title contenders lined up in close formation with AJ Allmendinger leading championship leader Sebastien Bourdais and Englishman Justin Wilson.

Katherine Legge was a superb eighth, nearly two seconds quicker than her teammate Oriol Servia while Mario Dominguez was 15th on his Rocketsports Racing debut and Juan Caceres 17th on his series debut for Dale Coyne Racing.