Sebastian Vettel gave Ferrari the early initiative over their rivals by beating Lewis Hamilton and Daniel Ricciardo to set the quickest time in a close Practice 1 ahead of the Japanese Grand Prix.

A threat of rain both during the session and particularly in the afternoon meant the morning was busier than usual with teams conducting a run plan more typically seen in Practice 2.

That meant early runs on the middle of the three compounds for some and on the softest for those who have gone more aggressive with their tyre allocation and immediately it was clear Mercedes, using the Softs, look more comfortable as both cars moved to the top during this initial phase.

A clearer picture would emerge, however, as teams opted to complete qualifying simulations on the Supersoft early due to the incoming weather. Hamilton would initially beat Daniel Ricciardo's Red Bull to go fastest but that would be beaten by Vettel after a mid-session red flag caused by Carlos Sainz hitting the barrier on the exit of the Hairpin.

The German would be slightly held up by Marcus Ericsson at the end of his lap but he head enough in the first two sectors to hold a two-tenths of a second advantage with a 1:29.166s.

The Ferrari, Mercedes, Red Bull order would be repeated with their teammates as Kimi Raikkonen led Valtteri Bottas in fourth and fifth. Max Verstappen appeared to have battery charge problems on the out-lap during his Supersoft tyre run and would then be finishing his lap just as Sainz crashed, with the two factors combining to leave the Sepang race winner down in sixth.

A tight midfield battle between Force India, Haas, McLaren and Renault emerged with the eight drivers covered by less than a second. Each would have a representative in the top 10 too as Esteban Ocon was seventh marginally ahead of Nico Hulkenberg and Romain Grosjean.

Stoffel Vandoorne would be two-tenths off the mini group in 10th as the Belgian, Kevin Magnussen, who overcame water pressure issues to claim 11th, and Fernando Alonso all lapped in the 1.31.2s bracket.

Sergio Perez had a muted start in 13th as Lance Stroll was able to beat Jolyon Palmer into 14th but Williams do look set for another difficult weekend. Felipe Massa was 16th with the Toro Rosso's 17th and 18th as Pierre Gasly was unable to beat Sainz's best time despite his crash.

Finally, the two Saubers brought up the order as Pascal Wehrlein had a half-second advantage over teammate Marcus Ericsson.

After the performance runs, some would start a race simulation before an increase in the rain towards the end brought most back to the pits. With conditions only expected to worsen, Practice 1 could well be the most representative session of the day and perhaps of the weekend as the bad weather is forecast to remain until Saturday morning.

Should that be the case, teams would have to base their tyre setup and strategies on the data from Friday morning with dry conditions expected for the race and that could give Ferrari and Vettel reason for optimism looking ahead.