Raheem Sterling revealed a t-shirt memorializing a young footballer after scoring the second of his three goals for England in a 5-0 victory over Czech Republic on Friday.
The tribute in a European Championship qualifier could lead to action by governing body UEFA, however.
Damary Dawkins, a Crystal Palace youth team player who had been fighting acute lymphoblastic leukaemia for four years, died on Sunday aged 13.
Special night in so many ways ☝🏾✨ RIP Damary, gone but u will never be forgotten. ❤️ pic.twitter.com/AIJ0YVi5SY— Raheem Sterling (@sterling7) March 22, 2019
Sterling's t-shirt under his England jersey had a photo of Dawkins and the message "May your soul rest in peace."
The laws of football state that "players must not reveal undergarments that show political, religious, personal slogans, statements or images, or advertising other than the manufacturer's logo."
The law introduced in 2014 states that an offending player has to be sanctioned by the competition organiser.