Sebastian Vettel admits that the back-to-back DRS zones at the Korea International Circuit could cause him some problems as he attempts to take another step towards a fourth F1 world title.

The German starts from his sixth pole position of the season and, while many believe that he will once again drive away from the pack, as he did in Singapore two weeks ago, Vettel remains wary that the introduction of a second DRS zone on the main straight could provide his rivals with a chance to keep him in check.

"To be honest with you, it largely depends on the conditions, the wind," he noted, "I think we had a race two years ago where there was a massive head wind, [and] it's a long straight from turn two down to the hairpin in turn three.

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"Obviously, it gives you flexibility to have the DRS zones right after each other, and on two quite long straights, so we'll see. I think you can pick your corner, but there's another straight after that where you could lose the position [where] you gained it in the first place. The same goes for turn one as it does for turn three."

Worryingly for those hoping to peg back the German's championship advantage, Vettel reckons the Red Bull improved through day two of the meeting.

"Yesterday, I wasn't entirely happy, the car was good but I think we managed to improve it today and we seem to be able to go with the track, which is usually the most important thing," he confirmed, "The track ramped up throughout qualifying and I think we picked up pace and just went quicker."

Despite that, Vettel refuses to be believe that he is the dominant force ahead of the race - particularly with Red Bull team-mate Mark Webber penalised back to 13th on the grid at a circuit he enjoys - citing the unusual nature of the Korean track as a reason why it could remain close at the front.

"I think it's a difficult lap," he admitted, "You obviously start with a lot of straights and then you've got all the corners at the end, so it's difficult to get the lap together, to get a clean lap in. There are many chances at the end to make small mistakes, which lead into another and into another..."