Keith Cronin was quickest in four of the day's five stages to lead the Rally Isle of Man - the final round of the British Championship.
Cronin and co-pilot Mikie Galvin drove their M-Sport Ford Fiesta to a 7.5-second advantage over Welsh crew Matt Edwards and Darren Garrod.
Sweden's Fredrik Ahlin and Torstein Eriksen, who lead the championship, are a further 16 seconds back.
Crews face a 14-hour day involving 11 stages on Friday.
The day will culminate with the iconic double run through Castletown in the south of the island.
More than 150 rally crews are competing in the three-day event with the British Rally Championship decided on Saturday.