Alex Ferguson has promised that Manchester United will go for broke next Tuesday at Old Trafford in search of a Champions League final place.

The semi-final against Barcelona is finely balanced after a 0-0 draw in the first leg at the Nou Camp, with Cristiano Ronaldo's penalty miss after three minutes depriving United of a precious away goal.

Ronaldo fired high and wide and was left frustrated after failing in his bid to improve on his remarkable 38-goal tally.

Barcelona soon recovered from that scare and had the majority of possession but failed to hurt United.

Asked if his side would be more aggressive in the return match, United boss Ferguson said: "Absolutely, no question about that. The game now starts at Old Trafford - it's the deciding game.

"A scoring draw and we're out, a loss and we're out, but the big bonus is that if we win we are through to the final. At Old Trafford, with the atmosphere, it will be quite different to this game.

"Barcelona have a lot of possession in all games, especially at home, and I am satisfied with the clean sheet - it was a professional performance."

Ronaldo, who insisted he did not alter his penalty-taking technique, vowed to make amends in the second leg.

"I didn't change," he said on Sky Sports 2. "I scored a few penalties in that side but today I didn't score - no problem. Now I'm going to score in Manchester."

Ronaldo insisted he should have been awarded a second penalty later in the first half when he was bundled over by Rafael Marquez.

"I think he touched me," he said. "But the referee didn't give a penalty. I don't know why, I don't understand."

Ronaldo added: "It was a tough game. Barcelona played very well, they kept the ball a lot. But I think we defended well, we played well as well; 0-0 is a good result."

Ferguson revealed that Nemanja Vidic is likely to miss the Premier League title showdown with Chelsea at Stamford Bridge on Saturday.

The defender received hospital treatment for a stomach problem and was forced to miss the match in Spain.

In his absence, Wes Brown partnered Rio Ferdinand in central defence and the pair were rock solid as Barcelona sprayed the ball around trying in vain to find a way through.

"Nemanja went 24, 36 hours without eating," Ferguson said.

"I don't think he'll be ready for Saturday - that's the situation, it's a stomach infection. Before training yesterday, he had very severe stomach pains, so we sent him off to a hospital only about a mile away.

"We felt that was the best place for him to go. He was kept in until late at night and then they let him go."