"I thought Kuyt would get to the cross at the near post," the 28-year-old told iDNES after Chelsea's seventh loss of the season.
"I wanted to get out so that I could react but he missed the ball, which flew past very fast and at the other post I had no chance then. It was clearly my mistake. I was there later than I should have been.
"I made a clear error, there is nothing more you can say about it."