Hamilton just sixth in Friday running; Vettel tops Ferrari one-two; Qualifying starts at 10am on Saturday morning
Monday 2 October 2017 14:37, UK
Mercedes will be working long into the night ahead of the Malaysia GP weekend to discover "the gremlin" which grievously hampered their car in Friday practice.
The world champions were inexplicably off the pace on the first day of running at Sepang. Title leader Lewis Hamilton was just sixth fastest, behind the Ferrari and Red Bulls as well as McLaren's Fernando Alonso, and finished the day over one second behind championship rival Sebastian Vettel in the charts.
Ferrari set searing pace as Mercedes struggle
The result amounted to one of the team's most uncomfortable - and unexpectedly difficult - days in recent memory.
"There is a gremlin in the car," team boss Toto Wolff told Sky F1. "It was a very difficult session for us. We struggled from the get go this morning, in the wet, in the dry, on all tyres. We need to find out overnight what it is.
"There is a fundamental issue in the car that we need to find out."
Wolff then added in the team principals' press conference: "It is certainly one of the worst Fridays I can remember."
Hamilton slithered off track at one stage with both the Englishman and team-mate Valtteri Bottas complaining of a general lack of grip.
"The car was terrible in the rain," said Hamilton. "At the last race the car was really good in the rain, this morning the car was just as bad as it was in P2 in the dry.
"It doesn't work in whatever condition at the moment, so we've really got to understand why and make some changes.
"It's a very unusual scenario - I don't remember the last time we had this kind of feeling. The engineers will do a lot of analysis tonight and the guys back at the factory will be working overtime to try and understand it to see if they can rectify it."
By pertinent contrast, Ferrari enjoyed a trouble-free Friday as Vettel led a one-two ahead of team-mate Kimi Raikkonen after Red Bull had topped a wet Practice One.
"It's been a decent day," said Vettel. "Red Bull looked very fast in the mixed conditions this morning, in the damp and wet on the intermediate tyres."
Raikkonen said: "Everything went smoothly, not too bad. I thought my car was not too bad but we didn't do too many timed laps and we can go an awful lot faster."
Questioned about Mercedes' apparent struggles, Vettel expressed both surprise and a degree of suspicion.
"Fridays are when you play around and try some things," he said. "It looked like both Mercedes were struggling in morning and afternoon so I'm pretty sure they will be fine tomorrow."
Red Bull driver Daniel Ricciardo added: "I think Mercedes were quite heavy today. I don't know if it's legit or they're playing some games."
The Red Bull cars of both Ricciardo and Max Verstappen, fastest in P1, appeared far more comfortable in the rainy conditions of the morning with the pair falling nearly a second adrift in the afternoon.
"In the dry we had quite a big gap to Ferrari," said Ricciardo. "We need to find a better compromise on low fuel and high fuel.
"We can still improve a lot. Ferrari are strong, Mercedes are a bit strange for now but I'm sure they'll get quicker tomorrow so we need to improve.
"We can still find hopefully half a second somewhere and then we can be more in the fight. We are close but we're not quite there. If it rains we are there, if it's dry we need to find some speed."
