Simon Kjaer's last-gasp equaliser gave AC Milan a dramatic 1-1 draw at Manchester United, handing the Italians a great chance of reaching the Europa League quarter-finals.
Inter Milan finished bottom of their group with just one win and missed out on a place in the Europa League.
Should Real Madrid suffer a humiliating group stage exit, ending their remarkable run as the only team to ever avoid elimination at this phase, coach Zinedine Zidane's future will be at risk.
Zinedine Zidane rubbished suggestions he could walk away from Real Madrid and said the Spanish giants did not deserve to lose after going down 2-0 to Shakhtar Donetsk on Tuesday
Shakhtar Donetsk were without 10 first-team players and nine members of staff due to coronavirus infections but recorded a remarkable win over Real Madrid, after scoring three times in 13 first-half minutes.
Lautaro Martinez and Romelu Lukaku's prolific partnership has been the source of much of Inter Milan's success and they took their tally to a combined 54 for the season.
Sevilla qualified for the semi-finals of the Europa League on Tuesday after Lucas Ocampos' late header broke Wolverhampton Wanderers' hearts, while Shakhtar Donetsk thumped Basel 4-1 to join the Spaniards in the last four.
Manchester City made a flying start to the Champions League campaign with a 3-0 win against Shakhtar Donetsk.
Manchester United spent USD 66 million on buying Fred from Shakhtar Donetsk in June but he has made just six Premier League starts.
Juventus have maximum points after three games in Group H, and host Mourinho's side in Turin next.