Teenage Liverpool striker Michael Ngoo was booked after revealing a T-shirt tribute to the Hillsborough victims during an Under-21 match at Chelsea on Friday night.
Ngoo, 19, scored the final goal in a 4-1 Liverpool victory at Brentford's Griffin Park, then removed his shirt to reveal a message which read '96 reasons 4 justice'.
Official guidelines state that referees should show a yellow card to players who take off their shirt, but the crowd booed the booking and cheered the player.
The incident came two days after the Hillsborough Independent Panel released a report into the 1989 disaster, in which 96 Liverpool fans died.
