Jenson Button labeled his exit from the Belgian Grand Prix as a 'massive blow' to his title ambitions, after saying he did not know what know Sebastian Vettel was up to.
The reigning world champion was forced to retire from the race on lap 16 after he was sideswiped by Vettel under braking for the Bus Stop chicane when his Red Bull Racing rival lost control in their fight for second place.
A deeply disappointed Button, who had been nursing damage to his front wing before the incident, said the situation was hard to accept.
"I don't know what happened with Sebastian," Button told reporters after his exit. "All I felt was a big bang in the sidepod. It ripped the radiator out I think and I lost drive completely.
"It was a very strange incident. I don't know what he was doing really. It's a massive blow - a massive blow. It hurts quite a bit really."
Although slowed by the damage to his front wing, Button reckoned he was still on course for a good result as he held up his pursuing drivers.
"It was looking really good," he explained. "I had a good start and had a good fight in wet conditions. I was able to find grip better than other people in wet conditions. I had a damaged front wing which meant I had to put maximum front wing angle in the car, which made the rear twitchy but didn't give me any more front really.
"It was tricky to keep them behind, but I was doing a pretty good job, I thought. We were going to change the front wing at the stop."
Vettel was given a drive-thorugh penalty by the race stewards for causing the accident.