Hamburg - German referee Wolfgang Stark Wednesday defended his performance in Tuesday's Champions League semi-final between Barcelona and Chelsea after coming in for criticism from the Spanish side.

Barcelona coach Pep Guardiola criticised Stark for some of his decisions, saying the referee should have sent off fellow German Michael Ballack for a foul which he claimed warranted a second yellow card.

But Stark told German Press Agency dpa the foul on Andres Iniesta was not a bad one and that UEFA president Michel Platini was pleased with his officiating.

"It was a hard-fought game in certain situations but that is quite normal," Stark, 39, said of the first-leg goalless draw at the Camp Nou stadium.

Stark said he saw no really bad fouls during the game and that he and his team of officials had been told by a UEFA delegate that Platini was "very satisfied" with the refereeing.

Ballack was booked in the first half but Guardiola felt he should have been shown a second yellow card after he caught Iniesta in the face, bringing the midfielder down just outside the penalty area.

"For me it was not a yellow card. It was a normal foul for which I gave a free-kick," he said.

At the post-match news conference, Guardiola said the German referee was wrong to book defender Carles Puyol, who is now suspended for next week's second leg, and Yaya Toure, and that he should have sent off Ballack.

"It can't be allowed to happen that the team that tries to play ends up with the same number of cards as the one that just fouls," Guardiola.

"The incident with Ballack was scandalous. Andres was heading into the penalty area through on goal. It was a very clear second yellow." (dpa)