Lewis Hamilton followed up his impressive Practice One showing by clocking the fastest time in second practice in Korea on Friday.
The Mercedes driver's best time of 1m 38.673 was 0.108s faster than Sebastian Vettel's quickest effort of 1m 38.781 for Red Bull, as both drivers trimmed their times by switching from the medium compound Pirelli tyres to the supersofts.
The second Mercedes of Nico Rosberg was just another 0.016s slower on 1m 38.797s, whilst Mark Webber recorded a 1m 38.844s in the other Red Bull.
Aside from spins for Sauber's Esteban Gutierrez and Caterham's Charles Pic, the 90 minute session was relatively uneventful as teams and drivers concentrated on their race simulation runs.
Felipe Massa was faster than Ferrari team mate Fernando Alonso; the Brazilian made up for time lost this morning with a fifth-fastest 1m 39.114s, with Alonso's 1m 39.444s slotting him seventh behind Romain Grosjean's Lotus on 1m 39.226s. Kimi Raikkonen was eighth in a Lotus E21 that was rebuilt after his morning shunt, and he recorded 1m 39.757s. The runners below 1m 40s were completed by Jenson Button, whose McLaren again ran well as he worked down to a promising 1m 39.774s.
Adrian Sutil and Paul di Resta were very evenly matched in their Force Indias, the German posting 1m 40.006s to the Scot's 1m 40.007s. Sergio Perez was next up in the second McLaren, on 1m 40.152s, which narrowly beat Gutierrez's 1m 40.186s. Gutierrez's team mate Nico Hulkenberg lost places compared to the morning, and was 14th on 1m 40.210s in the other Sauber C32, with Jean-Eric Vergne and Daniel Ricciardo 15th and 16th for Toro Rosso on 1m 40.446s to 1m 40.552s.
The Williamses were next, with Pastor Maldonado continuing to head team mate Valtteri Bottas, 1m 41.117s to 1m 41.289s.
The timesheet was filled out by Caterham and Marussia; Giedo van der Garde the quicker of the green cars on 1m 42.461s to Charles Pic's 1m 42.798s, as Jules Bianchi took back his Marussia from Rodolfo Gonzalez to record 1m 43.108s to team mate Max Chiltons 1m 43.441s. (Formula1.com)