Bruno Senna believes Sebastian Vettel cannot have seen him in their early clash in the Brazilian Grand Prix.
Vettel's world championship chances came under threat after his Red Bull made contact with Senna's Williams at Descida do Lago on the opening lap.
Senna had been battling with Paul di Resta at the time, while Vettel had already fallen to seventh due to a poor start.
"It was a great start and I had a good run on di Resta into Turn 4," said Senna.
"Unfortunately Sebastian was on the outside and dived to the apex, and obviously didn't see me so hit me very hard.
"I spun and was hit by [Sergio] Perez. Not the end to the Brazilian Grand Prix I wanted, but sometimes in racing that happens."
The incident spun Vettel to the tail of the field and caused damage to his Red Bull. He was nevertheless able to continue and was running seventh at half-distance.
