Manchester United missed the penalty, but Barcelona the opportunity. Cristiano Ronaldo could have decided this match in the third minute but shot wide and, metaphorically, Barcelona did much the same in the remaining 87. Several chances in the second half went begging, enough to win comfortably, and Sir Alex Ferguson’s team will surely not be as tame as this at Old Trafford in five days’ time.

Nor can they afford to be if they want to reach the final in Moscow next month. Despite Ronaldo’s aberration from the spot, when the match was still cold, United will consider themselves fortunate to have taken a draw from the Nou Camp last night. Barcelona were the better team by some distance, had the best chances from open play and, now needing to score an away goal to progress on aggregate, should in no way be undervalued. It needed Edwin van der Sar to be at his best in the United goal to keep them at bay here and one goal at Old Trafford could prove costly for Ferguson’s men. It has in the past.

A goalless first leg is not the result it seems at first glance. United earned one in Monaco, Madrid and Volgograd in previous campaigns and lost all three ties. Only once, against Panathinaikos, has a goalless away draw set United up for a home victory and Barcelona have as much to offer as any team in Europe beyond home soil. United will be hugely vulnerable to every counter-attack and when a team boast the attacking capacity on display here, that is no idle threat. Thierry Henry as a substitute is some luxury and his arrival in the 76th minute produced two shots from range that needed the best attention of Van der Sar.

The sole complaint from United on the night was that Ronaldo should have had a penalty in the 28th minute, after a clumsy collision with Rafael Márquez as they tussled for a loose ball. Ronaldo’s fall was so mannered, however, that it probably undermined his case and Massimo Busacca, the Swiss referee, waved play on. Considering what happened when Ronaldo did win a penalty, however, who knows if it would have made a difference. He seemed greatly affected by his early miss, had a quiet game by his standards and may not have been in the right frame of mind to accept redemption.

And now, the familiar debate will resurface. Does Ronaldo have the temperament for the biggest matches? Does he choke when the pressure is really on? There will have been a million or more armchair experts taking a self-satisfied swig from their lubricant of choice and crowing: “I told you so.” It is all a little unfair, really.

The case for the defence, for mitigation, would argue that few players would be cool and composed so soon on such a huge occasion. One minute Ronaldo was in the dressing-room thinking about United’s biggest match of the season, the next he was standing over the chance that could decide it. So he faltered. So nerves got the better of him. How many times has that happened in this campaign? Give the kid a break.

There was barely 90 seconds on the clock when Ronaldo was given the chance, we now know, to win the match. First, he took a phenomenally ambitious free kick from the best part of 40 yards, which deflected off Barcelona’s blockers for a corner. When that came in, his header was smothered by the outstretched arms of Gabriel Milito and when Busacca pointed to the spot, Ronaldo picked up the ball and prepared to take the weight.

Unsurprisingly, the home team’s support was not best pleased and the wall of noise that greeted Ronaldo as he assessed the situation felt like Anfield squared. Remember his penalty against Arsenal at Old Trafford in the league recently, the one when he checked his run halfway before burying the shot, was asked to retake, and had the audacity to repeat it, right down to the cocky pause in mid-stride? Well, think the polar opposite and you have a mental picture of what happened here.

Ronaldo ran up without delaying, in conventional fashion, aimed high, in conventional fashion, and sent his effort wide, in conventional fashion. Well, if you have been brought up on English penalty-takers, that is.

And that was pretty much that from United, save a shot from Michael Carrick that struck the side-netting midway through the second half. For the rest of the match, the noble Paul Scholes aside, they surrendered the heart of midfield and the lion’s share of possession to Barcelona, whose fall as a power in Champions League football has been seriously overstated. Key players such as Ronaldinho and Henry were missing from the starting line-up, but they had enough talent to give United the skilful battle of equals that they do not face in the Barclays Premier League, unless Arsenal are at their peak.

Lionel Messi was in scintillating form for an hour, particularly for a player so recently returned from injury, Deco belied the rumours that he had turned into a workshy dilettante since Barcelona’s Champions League win in 2006, while Andrés Iniesta and Xavi Hernández pulled the strings beautifully in midfield. Yaya Touré, the brother of Arsenal’s Kolo, was a flawless screening presence in front of the back four, looking every inch the player his sibling once compared to Patrick Vieira. It is amazing that he is not with Kolo in North London, really. He had a trial with Arsenal, but they did not fancy him.

They would have fancied him last night as he kept United at arm’s length, their venom removed by the early disappointment. Barcelona, by contrast, buzzed around the United penalty area, always alert, always dangerous, and in the space of ten minutes missed four good chances from Gianluca Zambrotta, Xavi and Samuel Eto’o (twice). Messi left the field after an hour, by which time the point was made, though. United have a live one here: silly to think that it was ever going to be anything else, really.