Portugal Winger Richard Quaresma and defender Miguel Lopes had a training ground bust-up, days ahead of their semi-final against either Spain or France.
During one drill, Quaresma was pushed to the ground by Lopes whereupon the winger kicked out at the defender's legs. Team-mates quickly stepped in to prevent the situation getting worse.
Defender Ricardo Costa stood in front of Quaresma to calm him down while coach Paulo Bento also got involved.
"It's just normal things that happen in training," Costa said at a news conference later. "Things got a bit heated between two players. We're pumped up, we always want to win and sometimes small things happen.
"Everything's sorted now. We all want to play (in the semi-final) and sometimes stuff happens."