Sergio Ramos and Ruud van Nistelrooy struck for Real and Robben said afterwards: "We cannot be happy with the result because we had the chance to score more goals and should have played a lot better.
"In the first-half we started very well and scored a goal quickly. But then we created no concrete chances. We should have finished the first-half with three or four goals.
"It's good to start with three points in this competition, but I repeat, I'm not happy with either the result or with the game we have played. We are at the beginning of the Champions League and yet we must improve."