The duo came together on the exit of the hairpin on lap one, when di Resta got to the outside of Sutil as the German tried to pass Nico Hulkenberg.
Sutil drifted wide and banged wheels with di Resta, sending the Scot bouncing over the grass.
Di Resta said his subsequent "remarkable" pace proved that the collision had been costly.
"Unfortunately the contact with Adrian at the hairpin set us back three or four places," said di Resta.
"From there I just couldn't get unleashed. I had to settle in with everyone else.
"But that third stint was awesome. We were just able to pick our way up and caught a lot of seconds on the cars in front. That's what eventually got us the eighth place. It was quite a remarkable recovery.
"I think we can be confident that we could have done a very good job if everything had gone to plan."
Sutil felt di Resta had put himself in a risky place when they tangled.
"There's not much to say," said the German. "I didn't really see anything, just felt a hit on my rear tyre and looked in the mirror and saw Paul there.
"I don't know what he was trying."