Barcelona became the first team to reach five consecutive Champions League semi-finals, potentially setting up another meeting with Chelsea. A 52nd-minute goal from Andrés Iniesta and the two earlier penalties that gave Leo Messi 14 Champions League goals for the season, equalling José Altafini's 50-year-old European Cup record, took them to a 3-1 victory over Milan. As a bonus Barcelona took up their now familiar slot without suspensions and without the returning Zlatan Ibrahimovic scoring against them. Instead the Swede departed raging against the referee.

The night ended with songs and even an olé or two. "We had 21 shots; we made lots of chances and on a different day the result might have been much bigger," Pep Guardiola said. But it had not always felt so comfortable. Ibrahimovic caused problems and, at least until Iniesta struck, nerves invaded Camp Nou. The debate about the second penalty will run, too.

According to Massimiliano Allegri, it had been awarded "too easily" while Ibrahimovic went further. "Now I understand why [José] Mourinho behaves the way he does at the Camp Nou," he told Swedish television. "If Mr Ibrahimovic says that it's thanks to the referees, fine," responded Guardiola. "I have seen them on the television and they are two penalties. Sometimes they don't blow those but pulling someone's shirt in the area is a penalty. And it's five semi-finals in a row now. You talk on the pitch."

Guardiola said he was proud of that record but he was reluctant to be drawn on Barcelona's potential opponents. "It is too early," he said. "Benfica are a very good side who caused Chelsea problems in the first leg, so let's wait and see. Whoever it is, they will be very difficult opponents."

For almost an hour Milan, too, were. The 0-0 first-leg draw left the tie on an edge, a single goal meaning the greatest of swings. Barcelona had a dilemma: go for goals or go for control? Guardiola had insisted "our objective will be to create chances". The reason was simple: Milan, he said, would score. There was little point in protecting a slender and vulnerable lead.

Instead Barcelona had to pull Milan about and create space. Isaac Cuenca gave width on the left and Dani Alves on the right, effectively leaving a high three-man defence. Messi and Cesc Fábregas were part centre-forwards, part central midfielders, often creating a line of four up front: Cuenca, Fábregas, Messi, Alves. The plan was familiar: occupy space outside to create space inside. It was also risky. Milan spread three across the middle with Ibrahimovic, Kevin-Prince Boateng and Robinho ahead. When they progressed, there was space.

For Barcelona there were nerves, even after taking an 11th-minute lead. Messi blocked Ignazio Abate's pass and the rebound became a through-ball, the chase for it a straight sprint. Messi beat Philippe Mexes. He laid it to Xavi who nudged it to Iniesta. When the ball ran free to Messi, Antonini brought him down. Messi's low penalty squeezed in between the post and Christian Abbiati's hand.

Barcelona wanted an early goal, but they stAnd Guardiola was right: Milan did score. ill wanted another. Abbiati had made a handful of saves, even if few were outstanding. Just after the half-hour Ibrahimovic turned and assisted Antonio Nocerino, who side-footed past Victor Valdés. Barcelona had been looking for the second goal anyway but now desire became an obligation. They needed two, not one.

The second came from another penalty just before half-time and the initial reaction was surprise. Sergio Busquets was held by Alessandro Nesta at a corner and Bjorn Kuipers blew. At first it was not clear what the referee had given but Milan's shocked players surrounding the referee was a clue. The wait for Messi was a long one but he hit the other corner.

If Guardiola assumed the risk before, now he sought to minimise it, immediately sending Alves to full-back. Barcelona still attacked and so did Milan – in the first minute of the second half they were appealing for a penalty of their own when Alves lunged at Robinho. Soon, though, Messi's deflected shot squirmed to Iniesta, who controlled and shot past Abbiati to make it 3-1. At last Barça had the cushion they craved; they could step down off that knife edge and keep the ball. The sense of impending doom every time Milan attacked largely evaporated.

The control was Barcelona's and they pressed high, denying Milan the oxygen to attack them, refusing to let the Italians inject intrigue into this tie. The best chances fell Barcelona's way, Thiago Alcantara and Adriano shooting wide when clean through. There were few other opportunities. Barcelona no longer needed to seek them; they had earned the right not to. The European champions had sought out and earned their place in the semi-final – again.