Aaron Wan-Bissaka will miss Manchester United's trip to Atalanta as well as Wednesday night's fixture with Villarreal after UEFA decided to extend his suspension.
The right back was sent off against Young Boys on matchday one, costing United a position of strength after his side had taken the lead through Cristiano Ronaldo, only for the Swiss side to eventually seal a shock comeback win in stoppage time.
With Ole Gunnar Solskjaer's team preparing to face last season's Europa League final opponents Villarreal on Wednesday, UEFA's Control, Ethics and Disciplinary Body announced Wan-Bissaka's suspension had been extended for 'rough play' in the previous gameweek.
In his absence, Diogo Dalot will likely be given a chance at right back in United's next two Champions League games.
The news comes a day after Kevin De Bruyne, playing for United's local rivals Manchester City, avoided a red card for a similarly robust challenge on Paris Saint-Germain's Idrissa Gueye during the French side's 2-0 victory.
While United knew Wan-Bissaka would be absent this week, his extended ban is another blow for a side looking to put their poor start in Europe behind them. A number of important squad members are also currently sidelined through injury.
Captain Harry Maguire is definitely out while Luke Shaw is a doubt, meaning Solskjaer could be without three of his four first choice defenders. Victor Lindelof and Alex Telles will come in, and going further forward Jadon Sancho may be given a start on the wing following their disappointing attacking effort in the 1-0 defeat to Aston Villa at the weekend.
That loss means the Red Devils have now won just one of their last four matches in all competitions, though they are only one point off Premier League leaders Liverpool.