UEFA has charged Benfica after their supporters set off fireworks during the 2-0 defeat against Manchester United at Old Trafford on Tuesday.
United inflicted a fourth straight Champions League defeat on Benfica to leave the Portuguese club bottom of Group A without a point.
And Rui Vitoria's side could face punishment from UEFA following their supporters' use of fireworks at Old Trafford, with the governing body set to make a decision on Nov. 16.
A UEFA statement read: "Disciplinary proceedings have been opened following the UEFA Champions League group stage match between Manchester United FC and SL Benfica (2-0), played on Oct. 31 in England.
"Charges against SL Benfica: - Setting of fireworks - Art. 16 (2) of the UEFA Disciplinary Regulations.
Benfica flares Old Trafford Matthew Peters/Man Utd via Getty Images
"This case will be dealt with by the UEFA Control, Ethics and Disciplinary Body on Nov. 16."
Last month Basel were fined €12,000 after their fans let off fireworks before their Champions League opener at Old Trafford in September.
St Etienne were fined €50,000 in March after their fans set off fireworks, in addition to charges for throwing objects and the improper conduct of supporters, in their Europa League round-of-32 clash at Old Trafford.
Information from the Press Association was used in this report.
Source: espn.co.uk