Shakhtar Donetsk midfielder Taras Stepanenko declared his friendship with Ukraine team-mate Andriy Yarmolenko over after ugly scenes in his side's win over Dynamo Kiev.
Yarmolenko kicked out at Stepanenko after a goal celebration in Shakhtar's 3-0 win in the Ukrainian Premier League on Monday.
Both players were sent off after a scuffle between the teams, with Yarmolenko having earlier committed a crude challenge on the 26-year-old.
Stepanenko said he was no longer friends with Yarmolenko, putting Ukraine coach Mykhaylo Fomenko in a tricky position ahead of Euro 2016.
"As for the incident at the end of the match... Lviv is currently considered to be our home ground, I just showed the crest of my team," he said.
"No signs, no bad words. Then I calmly ran to my goal, being hit once, two times, three times.
"I have not seen them, but they say it was Andriy Yarmolenko. Say a big hello to him!
"I think that my friendship with him is over after this incident. I forgot about it for the sake of the national team.
"But in this particular case, had it been my standing leg, he would have simply broken my knee cap.
"So I am saying without emotion and officially: my friendship with the man is over."
Ukraine have been drawn in a tough Group C for the European Championship, taking on Germany, Poland and Northern Ireland.