Marouane Fellaini has escaped UEFA punishment for throwing an arm at Emre Can towards the end of Manchester United's Europa League first-leg clash with Liverpool.
The incident was not included in the match officials' reports so no action could be taken retrospectively.
BT Sport analyst Howard Webb, who officiated the 2010 World Cup final, said the act of violent conduct should have been a red card, but it was missed by all six officials at Anfield.
Liverpool won the first leg of their last-16 tie 2-0 at Anfield and the return takes place on Thursday, and Can was keen to downplay the incident at full time.
"It was just a small fight. It was ok. It was not a boxing ring punch," The German player said.
"Fellaini is a fair sportsman. He touched my throat with his elbow but it is okay."