The Football Association is studying video footage after Leicester's Danny Drinkwater appeared to elbow Valon Behrami on Saturday.
Drinkwater clashed with Behrami in the 67th minute of Watford's 2-1 Premier League win at Vicarage Road at the weekend.
The FA will also speak to referee Neil Swarbrick, who was only yards away but appeared to miss the incident.
The match official had shown Drinkwater a yellow card for fouling Behrami two minutes earlier.
Drinkwater could be charged with violent conduct by the FA if Swarbrick confirms that he did not see the incident.
That could lead to a three-match ban for the England international.
Drinkwater, who has won three caps for his country, missed out on Gareth Southgate's last England squad with a rib injury.
Leicester are 14th in the Premier League table and struggling to defend their title after picking up just three wins in their opening 12 games this campaign.