Swansea and Leicester have been asked by the Football Association to provide details about a tunnel clash between Ashley Williams and Riyad Mahrez on Saturday.
Swans skipper Williams, 31, and Foxes winger Mahrez had to be separated outside the home dressing room after Leicester's win at the Liberty Stadium.
Williams then attempted to follow Mahrez, 24, on to Leicester's team bus.
After the game, Swansea boss Garry Monk said he was unaware of the incident.
The players came together during the first half of Saturday's match when Williams attempted to wrest the ball from Mahrez to take a free-kick.
Referee Michael Oliver spoke to both men, but did not show either a yellow card.
Mahrez had already scored twice - and he completed his hat-trick in the second half as a 3-0 win sent Leicester two points clear at the top of the Premier League.
After the players clashed again following the final whistle, Williams brushed past reporters in search of the Leicester bus, but soon returned inside the stadium.