Korean Grand Prix: Red Bull aims to build on strong Friday pace

Vettel, winner of the last two grands prix in Singapore and Japan, pipped team-mate Webber by 0.032 seconds. The duo had a 0.3s margin over the rest of the field.

"We can be quite happy. It is extremely tight and we are happy with how everything went today," said Vettel.

"The track was changing quite a lot today so it is better than expected. This afternoon at the start it was quite slippery but then it got a bit better.

"All in all the car felt alright and obviously we will see what we can do tomorrow."

Having not finished on the podium since his British GP win, Webber said he was keen to make sure his practice form carried through the rest of the weekend. In Japan a week ago he joined Vettel on the front row but could only finish ninth after being punted off by Romain Grosjean on lap one.

"Hopefully we can stay ahead of the game and have a smooth run again tomorrow," he said.

"We had similar runs like this in Suzuka, but only one of us got the job done there so I am looking to do that on Sunday."

Both drivers added that the often-dusty Yeongam circuit appeared to be in better shape this year.

"I think it was OK," said Webber. "I was surprised the track was as good as it was; we have had worse venues to be honest on a Friday.

"The track wasn't crazy, though or sure the first run was not great.

"The track will change, but it is not our first grand prix so we will be ready for that."