Pep Guardiola has leapt to the defence of Barcelona ahead of the second leg of their Champions League semi-final against Real Madrid.

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

Dani Alves, Pedro and Sergio Busquets were all accused of unsporting conduct by Madrid, while the latter is reported 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 European football's governing body decided against taking action and also threw out the charges made by the Catalan club against Madrid coach Jose Mourinho.

In the absence of the Portuguese, who is suspended for tonight's second leg 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 (Barca) 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 very 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 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."

Barca midfielder Xavi also hit out at Madrid's protests to UEFA.

"The complaint from Real Madrid was a disgrace and it's logical UEFA have rejected it," he said.

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'm happy it's all over," Guardiola said.

And Xavi added: "We have hardly talked about football at all and that makes me sad."

Back on the pitch, 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.

"It's difficult, but we can beat Barca and we'll give all our strength in those 90 minutes to make it to the final," he said.