Kimi Raikkonen has been left baffled by Ferrari's sudden decline with both himself and now Sebastian Vettel suffering two retirements in three races.

The Finn was unable to start in Malaysia and, in Japan, a spark plug issue meant that Vettel had to retire from the race after just four laps.

Raikkonen started P11 at Suzuka due to a grid penalty for a changed gearbox, but recovered somewhat to P5.

"Our starting position today was not ideal," Raikkonen said.

"I did a decent start on the soft tyres and in the first lap I tried to gain some positions, but when I attempted to pass a Renault I ran wide and lost some places; so I had to make them back.

"The feeling in the car was a little bit tricky all the way through the race, not the nicest balance; some laps were ok, some others a bit more difficult.

Raikkonen then addressed the issues facing Vettel and the team as a whole.

"It’s quite tricky to follow other cars on this track; we did a fairly good job out of overtaking people but we were too far from those at the front. Obviously, the final result is far from being the best possible.

He added: "As for Sebastian, I don’t know what happened; we have made a lot of improvements over the last few years as a team, but now, for whatever reason, we suddenly seem to have technical issues coming out from nothing.

"It’s kind of weird, our cars are running perfectly and suddenly on Sunday there is an problem that nobody expects. There is some work to be done on that side. Then we are going to push until the last lap of the last race and we’ll see where we end up."