AC Milan captain Massimo Ambrosini slammed Barcelona's decisive penalty after last night's Champions League defeat.

The spotkick was awarded for an Alessandro Nesta shirt tug on Sergio Busquets while being in turn fouled by Carles Puyol.

"In every level and on every corner things happen, but the interpretation changes from referee to referee. There is no uniformity.

"It takes some courage to make such an important decision in a tie like this. There are always going to be some tugs on set plays and always have been.

"We knew Barcelona are the strongest team in the world. We leave without regrets and there were differences between the teams over the two legs, but not all that much."