Barcelona coach Pep Guardiola today leapt to the defence of his players ahead of tonight's second leg of their explosive Champions League semi-final against Real Madrid.

The tie has been overshadowed by accusations and angry words from both camps over their behaviour during the powderkeg opening leg in Madrid last week.

Dani Alves, Pedro and Sergio Busquets were all accused of unsporting conduct by Madrid, while the latter is alleged to have racially abused Real full-back Marcelo.

Madrid published video evidence on their club website and made an official complaint to Uefa about the gamesmanship shown by Barca.

But Uefa chiefs ruled against taking action and also threw out the charges made by the Catalan club against Madrid coach Jose Mourinho, who was sent to the stand during the match.

In the absence of the Portuguese, who is suspended for tonight's tie and decided against speaking at the pre-match press conference, his assistant Aitor Karanka claimed Barca had gained an unfair advantage. He said: "The match has been overshadowed by Uefa's resolution – it's on another plane now.

"We have been punished with the suspensions for Pepe, Sergio Ramos and Mourinho, but there are Barcelona players who didn't respect the principles of fair play or who made racist insults, covering their mouths, who will be on the pitch."

Guardiola hit back, though, and said: "I know my players well and they are an example of professionalism and honesty.

"They can all make mistakes during the game, but they are exemplary human beings and in any case, the actions from the past are just that – in the past."

And the Barca coach says Mourinho should be aware, from his own time at the Catalan club, that players are brought through the youth system with the right values.

"Mourinho was here for five years and he knows our values – to win, fight and earn respect by respecting your rival," he said.

"They think we are unsporting, but I think completely the opposite. Here we teach our players manners from a young age."

Tensions have grown on and off the pitch over the last 17 days, but tonight's game will conclude the four-match Clasico series, which began on April 16 with a 1-1 draw in the Primera Division.

"I am glad it is all over," said Guardiola. Barca will be big favourites to reach the final after winning the first leg 2-0, but Madrid striker Karim Benzema believes Real can produce an upset.

He said: "We will give all our strength to make it to the final."