Chelsea defender Marcos Alonso's apparent stamp on Southampton striker Shane Long on Sunday is under the English Football Association (FA) investigation, it was reported on Tuesday.
Sky Sports said that Southampton coach Mark Hughes accused Alonso of almost breaking Long's leg in the challenge, which happened when Chelsea were 0 - 1 down in the English Premier League (EPL) game.
Referee Mike Dean did not book Alonso for the incident, which happened directly in front of the fourth official Roger East.
Chelsea came from behind to win 3 - 2, leaving Southampton five points off safety in the EPL.