Sebastian Vettel edged out Red Bull team-mate Mark Webber in the second practice at the Formula One Korean Grand Prix.
The reigning world champion was just 0.032 seconds ahead of Australian Webber but clocked in 0.328secs ahead of Ferrari's Fernando Alonso.
Britain's Jenson Button came in at fourth while fellow McLaren driver Lewis Hamilton finished a disappointing eighth having been fastest in the first practice session.
Michael Schumacher, who announced he would retire for a second time at the end of the current season last week, finished a credible fifth ahead of Saturday's qualifying session.