Both Granit Xhaka and Xherdan Shaqiri celebrated their goals for Switzerland against Serbia on Friday by making a nationalist symbol of Albania in a gesture likely to inflame tensions among Serb nationalists and ethnic Albanians.
Switzerland rallied to beat Serbia 2-1 at the World Cup, but Albania's national flag was at the centre of attention.
Xhaka and Shaqiri, both of ethnic Albanian heritage, put their open hands together with their thumbs locked and fingers outstretched to make what looks like the double-headed eagle displayed on Albania's flag. The thumbs represent the heads of the two eagles, while the fingers look like the feathers.
The players could face punishment if FIFA decides they were making a political statement. Shaqiri declined to discuss the matter after the game.
"I think about this, I don't want to speak," Shaqiri said. "In football, you have always emotions. You can see what I did, and it's just emotion, and I'm just happy to have scored the goal. I did it, and we don't have to speak about this."
Shaqiri was born in Kosovo, the former Serbian province that declared independence in 2008. Serbia doesn't recognize Kosovo's independence and relations between the two countries remain tense.
Xhaka's parents are originally from Kosovo and they are of Albanian heritage. His brother plays for Albania's national team.
Years of war in the Balkans sent many families to western European countries, including Switzerland. The Swiss have dozens of ethnic Albanians in their national football program.
Switzerland coach Vladimir Petkovic hoped the gestures wouldn't detract from the team's performance.
"You should never mix politics and football. You should always show respect,'' Switzerland coach Vladimir Petkovic said. "It's a wonderful atmosphere and a positive experience and that's what football should be about."
In the tournament's first come-from-behind victory, Xhaka made it 1-1 in the 52nd minute with a powerful shot through a crowded penalty area. Shaqiri added the other in injury time after running past the Serbian defense.
Serbia's players did not react to the eagle gestures at Kaliningrad Stadium.
"I don't have any comments," Serbia coach Mladen Krstajic said. "I don't deal with these things. I am a man of sports, and this is what I'm going to stay being."