2021–22 UEFA Champions League knockout phase
The draw for the round of 16 was held on 13 December 2021, originally at 12:00 CET. The draw featured multiple irregularities: Manchester United were mistakenly included in the draw for Villarreal's opponent (both were in Group F), and subsequently were selected; another ball was then drawn, with Manchester City chosen instead. In the following tie, Liverpool were mistakenly included in the draw for Atlético Madrid's opponent (both were in Group B), while Manchester United were incorrectly excluded. Later that day, UEFA voided the original draw due to a "technical problem" with the draw computer, and it was entirely redone at 15:00 CET.