Opalenica (Poland): Portugal defender Miguel Lopes and attacker Ricardo Quaresma came to blows during a training session on Saturday.
The incident happened towards the end of a team practice when the Braga man made a robust challenge on the Besiktas winger, who responded angrily to the tackle and aimed a kick at the right-back.
The two players went on to hurl verbal abuse at each other amidst a lot of pushing, and had to be torn apart by coach Paulo Bento and defender Ricardo Costa, who confirmed the rumours about the bust-up to the media.
"These are things that can happen in training," the Valencia centre-half revealed at a press conference.
"There was rather strong challenge for the ball. We’re virile, we always want to win challenges, and sometimes small incidents happen."
Portugal qualified for the semi-finals of Euro 2012 after a 1-0 win over Czech Republic and will meet the winner of the fixture between Spain and France in the next stage of the competition.