Highlights - Webber fastest in second practice
Korean Grand Prix, Yeongam, 22-24 October
Qualifying: 0500-0730 on BBC TV, Red Button, online and 5 live sports extra
Race: 0600-0915 on BBC One, Red Button, online and Radio 5 live
Mark Webber set the fastest time as championship leaders Red Bull responded to challenges from McLaren and Ferrari in practice for the Korean Grand Prix.
The Australian's best effort of one minute 37.942 seconds left him just ahead of rivals Fernando Alonso of Ferrari and McLaren's Lewis Hamilton.
Renault's Robert Kubica was fourth from Jenson Button, who lost time while McLaren fixed overheating on his car.
Red Bull's Sebastian Vettel was seventh quickest after suffering a puncture.
There was general praise for the new Yeongam circuit, which looks set to stage a fascinating race.
Webber positive after solid session
After two practice sessions, it seems clear that the layout of the track, with long straights in the first sector, flowing corners in the second and a tighter 'street circuit' design in the third, is equalising the performance of the top teams.
Red Bull, Ferrari and McLaren look closely matched, with Renault also looking strong in Kubica's hands.
The only concern, voiced by several drivers, is that the pit entry is very close to the blind final corner, leading to the possibility that cars could close up dangerously quickly on cars slowing to enter the pit lane.
Hamilton was confident that McLaren have improved their cars sufficiently to be able to match the Red Bulls for pace.
"I feel quite happy with the car and it feels quite strong today," he said. "We had some ride issues and some bits with the balance in P2 but we'll fix it.
"There might be another second in the track but I think we're pretty much there."
Webber said it had been a "positive" first day for Red Bull.
"We're optimistic with today's performance," said the Australian. "It's enjoyable to drive here, there are a couple of unique sections. The pit entry and exit is a little bit marginal to get on and off the track, but apart from that they've done a remarkable job."
Having spent first practice quietly accumulating data, Alonso immediately went to the top of the timing charts in the early stages of the afternoon session with a lap fully three seconds faster than his quickest effort of the morning session.
Hamilton, fastest in first practice despite minimal running, also improved to leapfrog the Ferrari before Sakon Yamamoto spun and stalled his Hispania exiting Turn 16, causing the session to be temporarily red-flagged.
When it resumed, Michael Schumacher emphasised his steady improvement in recent races by briefly going top before Button edged him.
There was less good news when the Englishman returned to the pit lane, overheating at the rear of the car requiring the attention of mechanics with extinguishers.
Vettel, on softer option tyres, was the first to break one minute 40 seconds, Hamilton - also on softs - one minute 39 seconds.
Alonso then set a mark of 1:38.1 before Webber, having spun exiting Turn 12, then took the times below 98 seconds before the teams settled into longer runs on higher fuel loads.
There are exclusive interviews with Lewis Hamilton and Sebastian Vettel on 5 live Formula 1 at 2030 BST on Friday. The show is available on 693 and 909 MW and to download after broadcast from http://www.bbc.co.uk/podcasts/series/cff1 or iTunes
Highlights - Hamilton fastest in first practice