Lewis Hamilton is at a loss to explain his lack of pace throughout the Russian Grand Prix weekend, but vowed to find answers before Formula 1's next race in Spain.
While Mercedes team-mate Valtteri Bottas produced a brilliant performance to secure his maiden F1 win at Sochi, Hamilton struggled with a lack of balance and an overheating car in fourth place.
The situation is further complicated by the fact that the two Mercedes were running similar set-ups.
"I can't explain it right now, but I will do some work over this week to fully understand it," said Hamilton.
"I have some theories about how it felt in the race and qualifying, some ideas, but lots of work will be done to figure it out."
Although Hamilton made a good start to challenge Kimi Raikkonen on the run down to Turn 2, he lost momentum as he got boxed in behind Sebastian Vettel under braking.
That kept him in fourth and, with his performance then further hampered by the need to cool the engine as he followed the Ferrari, Hamilton said from very early on in the race the chance of a podium was gone.
"From lap five onwards I just had to slow down and stay in fourth," he said.
"There was lots of turning down of the settings and the unit. I had cutting of one of the cylinders because of the temperatures.
"I was going to be fourth from very early on.
"I was slow from [Saturday] so that doesn't really change.
"I think I could kind of match those times at the front maybe, but whether I would have lasted as long... probably not with the set-up that I had.
"With the backing off for the temperature, it was losing seven tenths, maybe a second a lap."
The result left Hamilton 13 points behind title rival Vettel in the championship.
But the Mercedes driver said he was far more concerned about understanding why he was off the pace in Russia.
"I just don't think about it right now. It's not important," Hamilton said of the championship situation.
"We need to understand where the speed was this weekend, what went wrong with the set-up and come back fighting for the next race.
"There's still a long way to go, I'm still second in the championship.
"It's not the end of the world.
"Of course I need to recover the pace I had previously."