(Bopara) for the manner in which he played, backed up by Bresnan," said Cook after his side won the game by three wickets on Friday.
Bopara and Tim Bresnan conjured a critical 60-run partnership for the sixth wicket after England were in doldrums at 133 for 5, chasing 218 from 43 overs to win the rain-hit match.
"I thought Ravi played very well in a great little partnership with Bressy. But it was nerve-wracking...It's always nervy when you're sitting, watching and can't do anything about it.
"Morgan's absence allowed Ravi today to nail down a spot. He probably might not have been playing if Eoin was fit, so that's an encouraging sign."
Cook praised India's recovery but also felt his side could have done better when Dhoni and Ravindra Jadeja were stitching together than 112-run partnership.
"They probably did get too many, if we're being really honest with ourselves. After that Powerplay, I think they got 70-80 runs off the last eight overs which in an ideal world they wouldn't do. But it was a fantastic partnership. At times you think you could've been more attacking to try to get that wicket."
Cook admitted that they couldn't create many chances after top five wickets fell.
"But we didn't create another chance. Even if we'd had slips in there for a little bit longer, nothing went through there."
Cook was particularly taken in by the performance of Jadeja and believed his side would come up with an answer by the time the fourth one-dayer is played at Lord's tomorrow.
"He probably hadn't played much cricket going into the game and was very fresh and raring to go. He played very well. We've obviously seen a little bit more of him now than we had. So we hope we can bowl a little better at him on Sunday."
Indian spinners made a mark in this match with both R Ashwin and Jadeja keeping England batsmen on tight leash.
"They were very good. These conditions were unique in that some balls spun quite sharply and some others didn't at all without too much difference in the way they came out of hand.
"They were quite tough conditions to bat in and that rain break made us have to stop and regroup—and that might have just helped."
England, once again, were marvellous with the new ball in swing-friendly conditions and James Anderson, playing his 150th one-day international, was once again a very difficult customer to get away from.
"He was fantastic. It's his 150th game which is a great milestone. When the conditions are like that, he is outstanding at exploiting them."
"He and Bressy (Tim Bresnan) really set the tone. It was a great position to be in with them being 58 for five. In an ideal world, we would have got them for less. But sometimes the opposition are allowed to play well.
"We're delighted to be 2-0 up. But we've come here to win the series. We're another step closer to doing that."