DONETSK – Cristiano Ronaldo has expressed his frustration after Portugal were knocked out of Euro 2012 by Spain on penalties, but insists he was content with his own contribution.After a goalless 120 minutes in the semi-final, Spain won the shootout 4-2 with Ronaldo, scheduled to take the fifth kick, looking on. The Real Madrid star was not at his best during the game, and missed a fine chance to win it at the end of normal time.He told O Jogo: "It’s always painful losing on penalties but penalties are always a lottery and the one who has the best luck wins. We’re going out a bit frustrated because we could have gone to the final but we were unlucky."I gave my best as I always have done and that’s why I am happy with my own contribution. We must be proud because we played well but we didn’t have the luck we needed.”He later confirmed to the Portuguese TV network SIC: "I was going to take the next [penalty], but we missed two."It was just a question of me speaking with the coach. He said to me, ‘Do you want to take the fifth one?’ and I said ‘yes’. Sometimes I take the first, the second or the third. I agreed to take the fifth."I hope Spain win the tournament now because I have a lot of friends there and I play there and it will be a tough final for them. It felt very normal playing against Real Madrid players. On the pitch we are not friends, but outside we are.”