Lewis Hamilton was fastest in second practice for Sunday's Japanese Grand Prix but torrential rain meant the session was all-but a washout.
While rain threatened during first practice, there was enough time for Sebastian Vettel to set the pace on a dry track as he got the better of title rival Hamilton.
But in the period between the two Friday sessions a deluge hit Suzuka, leading to the first half of the afternoon being written off.
The rain abated to allow wet-weather running for the final 45 minutes, something which could prove useful if there is further rainfall ahead of qualifying tomorrow.
Hamilton then showed his prowess in the wet as he went quickest but the Briton was one of only five cars to set a full lap time.
The Mercedes man set a largely arbitrary time of 1 minute 48.719 seconds, with Force India duo Esteban Ocon and Sergio Perez and both Williams of Felipe Massa and Lance Stroll the only other drivers to register a time.
In the morning it was Vettel who would clock the fastest time in his Ferrari to draw first blood in his duel with Hamilton.
Even that session was curtailed as a crash for Carlos Sainz brought out the red flags as his stricken Toro Rosso was cleared away.
Hamilton had been faster for the earlier parts of the session but the Mercedes had to settle for second spot.
The Briton spoke on Thursday of preparing for "war" in his battle for the championship he currently leads by 34 points - and it may turn out to be a fight on two fronts as the Red Bull was also quick.
Daniel Ricciardo put his car third, just over 0.100seconds behind Hamilton with the second Ferrari of Kimi Raikkonen fourth.
Hamilton's team-mate Valtteri Bottas has recently admitted he has been struggling with the car lately and he set the fifth-fastest time of the morning.
Next up was Max Verstappen's Red Bull and ,with no-one improving on their times as the weather turned, Ocon was seventh ahead of the Renault of Nico Hulkenberg.
Romain Grosjean took ninth for Haas while Stoffel Vandoorne rounded out the top 10 for McLaren.