Müller sent off for flying kick
The Bayern Munich player was shown a straight red in the 74th minute for extremely dangerous play.
Update:

Thomas Müller was sent off in the 74th minute of the Champions League match between Ajax and Bayern Munich with the score at 1-1.
Terrible challenge from Müller
The Bayern player went flying, studs first, into Tagliafico’s head, making full contact with the Ajax player who was left prostrate on the ground. The Argentinean required staples to the resulting gash.

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Although the Müller claimed innocence, French referee Clément Turpin sent him straight off.
The red card levelled things up numerically, with Ajax already down to 10 men, Maximilian Wöber having been sent eight minutes earlier.