Lewis Hamilton admits he's perplexed by his drop in pace in Practice Two but is confident he'll be back on form come Saturday.
The McLaren driver set the pace on Friday morning, claiming the first P1 of the Korean Grand Prix weekend when he edged Fernando Alonso by three-tenths.
And although the afternoon's session began with Hamilton setting the pace but the end of the first ten minutes he was down in 14th place.
Slowly but surely the McLaren driver worked his way back up the order but by the end of the 90-minutes was only eighth, 0.885s slower than pace-setter Sebastian Vettel.
"The first session was fantastic so I don't really know what's happened in this session," Hamilton told Sky Sports News.
"We need to analyse and I need to look [at what happened]. Wind directions change but it didn't seem to affect other people so I have to try and figure that out.
"We've got time. We have to be calm tonight and try to figure out where we want to go in direction with the setting of the car."
With his team-mate Jenson Button finishing fourth, 0.387s, Hamilton is confident his MP4-27 has the pace needed to challenge at the front.
"Jenson obviously wasn't in such a bad position today so the car definitely has some pace there we just need to extract it," said the 27-year-old.
Vettel Leads Red Bull 1-2 In Practice Two