Jenson Button fears his McLaren's very strong race pace will be squandered by his poor qualifying result in Korea.
The Briton ended up only 11th on the Yeongam grid after a trouble Q2 featuring a mistake and a yellow-flag delay.
Button had been optimistic about McLaren's long-run performance on Friday, but suspects that speed will now be wasted in traffic.
"My long runs were very good yesterday. But it's disappointing to be so far back," he said.
"The race pace was really good yesterday. I think we were the quickest.
"That's why it's even tougher to be starting where we are."
Button accepted the major shame of blame for his qualifying result, putting it down to an early mistake in Q2. Yellow flags for Daniel Ricciardo's ailing Toro Rosso then interrupted his last run.
"I locked up, ran wide, and had to go down to first gear," he said.
"So I got to that sector [on the next run] thinking there was a couple of tenths there and should have easily been through.
"But it wasn't to be due to the yellow flags."