YEONGAM, South Korea - Kamui Kobayashi, whose place at Sauber in 2013 is in serious jeopardy, apologised to McLaren's Jenson Button and Mercedes driver Nico Rosberg after he sent both crashing out of the Korean Grand Prix.Kobayashi, criticised by other drivers in the past for his reckless driving, also had to retire from the race won by Red Bull's Sebastian Vettel.Kobayashi wrote on Twitter: "It was my mistake at (the) start. Sorry for Jenson and Nice (Nico).... Also to my team."'WHAT AN IDIOT!'Button's fine start from lowly 11th was wrecked when Kobayashi came flying down the inside, smashing into the McLare and destroying the suspension.Button said: "I've just been hit by Kobayashi. What an idiot!"Rosberg also retired due to the same incident. Kobayashi was forced into the pits for a new nose and tyre.He was then handed a drive-through penalty for causing the early carnage and bowed out when Sauber decided that the damage to his car was too extensive.The Sauber team tweeted before the race was out: "Kamui says with 4 cars side by side after the start he had nowhere to go but to brake at some point. He is very sorry for Jenson and Nico!"