Heikki Kovalainen retained top spot on Friday's Japanese Grand Prix timesheets despite not even venturing out for the second 90-minute session at Suzuka.

The McLaren driver joined Brawn twins Rubens Barrichello and Jenson Button in sitting out another wet hour-and-a-half as the weather won the battle for supremacy on a thoroughly damp return to one of the favourite stops on the F1 schedule.

Although there was never any doubt that Kovalainen's 1min 40.356secs lap from the morning session would continue to hold sway as heavy rain returned to Suzuka shortly before the afternoon outing, there wasn't even a threat to try and topple the Finn until the closing 25 minutes, as the entire field remained camped in their garages, waiting for a break in the precipitation.

Desperate to increase his knowledge of the tricky Japanese circuit, Jaime Alguersuari finally broke the monotony, but lapped some 16 seconds off the pace as he headed a growing stream of cars around the still soaking track.

With more and more cars passing over the surface, a drier - if never dry - line slowly appeared, allowing times to come down until Forcce India's Adrian Sutil finally claimed top spot with a 1min 47.261secs effort in the closing moments.

The German, who will be looking to atone for his Singapore effort this weekend, headed title outsider - and wet weather expert - Sebastian Vettel, with Force India team-mate Tonio Liuzzi, Lewis Hamilton and Kazuki Nakajima completing the top five. Nakajima's countryman, Kamui Kobayashi - making his debut for Toyota in place of the sick Timo Glock - improved to twelfth overall, although his best time was still some5.6secs slower than he managed in the morning session.