Adrian Sutil said he was unhappy with his performance at the Korean Grand Prix after failing to finish the event following a crash.
The Force India driver struggled with brakes issues and was involved in a series of incidents before retiring following contact with Sauber's Kamui Kobayashi. The incident cost Sutil a penalty, the German forced to drop five places on the grid in the next race.
"I'm not happy with my performance, it was not a good race for me personally, but I'm pleased that the team did well with Tonio and the sixth position," said Sutil.
"I was just struggling with my brakes all the time. I had so much brake force that I always locked up and it was hard to drive consistently. There were a lot of times I was off the circuit, or locked up, and then got past a driver and went off the road.
"In the end, I tried to overtake Kobayashi but lost the car on a patch that was a bit more wet than I expected and went into the side of him."
Teammate Tonio Liuzzi, on the other hand, enjoyed one of his best races of the season after finishing in sixth position.
"What a crazy race today, a bit like Australia back at the start of the year, and it was very fun to be out there," he said. "It was the right decision to delay the start as there was so much water on the track. Unfortunately we had to do a lot of laps behind the safety car after that but the track was so slippery that it was really hard under braking.
"Then at the end it was like a night race without any lights and the steering wheel lights were so bright it was almost dazzling! Even though there was so little grip I was able to get into a good rhythm and get a great result for the team.
"After all the bad luck we've had in this part of the year it's brilliant to be back in business and up there in the points again, extending our advantage over Williams and setting ourselves up well for the last two races."