Cristiano Ronaldo insists he will have no hesitation in accepting responsibility the next time Manchester United are awarded a penalty.

The Portuguese winger missed from the spot three minutes into the 0-0 draw against Barcelona in the Champions League semi-final, first leg last night.

But he has quickly shrugged off the mistake and turned his focus to the match at Chelsea on Sunday, where victory would effectively see United crowned Premier League champions for a second successive year.

"Next time I get a penalty, I will try and put things right. I am not scared," Ronaldo said. "I am always confident. I have 38 goals this season. It is not a problem if I miss one or two. I try to do my best in every game.

"Since I have been in Manchester I have scored 15 or 16 penalties, I think, and missed two. No-one has said anything to me because I always try to score, to play well."

That comment was backed up by Owen Hargreaves, who slotted neatly in at right back after being switched from midfield in a reshuffle forced by Nemanja Vidic's withdrawal through injury.

He said: "Cristiano has scored more than he has missed, so it is fine what happened. Maybe he should have had another penalty. But that was always going to be a difficult decision for the referee.

"He had already given one early in the game and we were the away team."

The contentious incident occurred in the 30th minute when Ronaldo fell to the ground under a challenge from Rafael Marquez. The United player chided Massimo Busacca, the Swiss referee, for not awarding a foul.

Ronaldo said: "While you have to respect the decision of the referee, he did not make the best decisions. Too many decisions went to Barcelona, he gave us nothing."

United rarely troubled Barcelona for the remainder of the tie but Ronaldo is convinced they will pose a more attacking threat at Old Trafford.

"It wasn't the best game in Barcelona but in Manchester we will try to win, " he said. "I'm sure the return game will be totally different. Barcelona won't keep the ball like they did in this match and we'll create more chances.

"It will be a different game and I'm sure we're going to play better. We are at home, we will have 75,000 people behind us. We will try to play good football and try to win."

Hargreaves is confident United will progress, too. "We are optimistic as we will play a lot differently than we did at the Nou Camp," he said. "We will attack Barcelona and see how they deal with it. They had a lot of possession but did not really penetrate us. We had a strategy and played really well."