Lewis Hamilton set the fastest lap in a soaking wet second practice session for the Japanese Grand Prix.
The start of the session was postponed for 45 minutes as water streamed down the pit lane and bubbled back out of the drains at the end of the paddock. A homemade paper boat race took place between some of the teams before the session got back underway with 45 minutes left on the clock.
Fourteen drivers went out on track, but only five set full lap times while the rest completed single or multiple installation laps. The two Red Bulls, two Haas drivers, Toro Rosso's Pierre Gasly and Mercedes' Valtteri Bottas opted against venturing out the pits at all given the risk of an accident and the limited information to gain.
Both Force Indias set times on three-lap runs on full wets, with Esteban Ocon 1.827s faster than teammate Sergio Perez. The two Williams drivers were next on track for a flying lap, with Felipe Massa on a three-lap run and Lance Stroll on a four-lap run. Of all the drivers that ventured out, Stroll got closest to disaster after aquaplaning on standing water on the run down to Turn 1 and taking a trip through the gravel. He came within a metre of the barriers but managed to avoid major damage.
Hamilton went out in what was arguably the best of the conditions to set a time 0.799s clear of Ocon on a three-lap run before a single-lap run towards the end of the session once the rain had intensified once more.
A dry first practice session saw Sebastian Vettel tip the timesheets, but he completed just one installation lap in the afternoon.