Liverpool winger Ryan Babel admits he was stupid to get involved in the row that led to his dismissal in his side's 2-1 Europa League quarterfinal defeat against Benfica.
Dutch international Babel was shown the red card in the 30th minute after twice putting his hands in the face of Benfica's Luisao at the Stadium of Light.
He was complaining about a nasty foul by Luisao on teammate Fernando Torres but Swedish referee Jonas Eriksson only booked the Benfica player before sending off Babel.
Two second-half penalties from Oscar Cardozo allowed Benfica to claim a first leg win, which left Babel regretting his actions.
"The referee told me the red card was for touching Luisao's face - that was it," Babel said.
"It was clear that Luisao had made an awful foul and all I wanted to do was back up Fernando.
"In the end maybe it was a stupid, silly thing for me to touch him in the face, but I think a yellow card would have been fair enough. But they are the rules.
"He came very loud and very close with his face and I just tried to back him off with my hand to say don't come too close.
"That's it and in the end, they made it bigger than it was. But it was a mistake by me, I will learn from it and it won't happen again."