Atletico Madrid defender Felipe was given a surprise red card against Liverpool after a cynical trip on Sadio Mane and seemingly a change of mind from the referee.
The Brazilian flicked his foot out at the winger on the counter-attack in the 36th minute, before running away from Dutch official Danny Makkelie who repeatedly whistled and asked the centre back to return to talk to him.
With the away side certainly expecting a yellow card, Makkelie then brandished a straight red to the astonishment of the Atletico players, resulting in a booking for dissent to ex-Red Luis Suarez.
UEFA have since confirmed that the red card was given for the foul on Mane and not the result of the later dissent.
At this point, Liverpool were 2-0 up late in the first-half following early goals from Diogo Jota and Sadio Mane.
Temperatures were certainly raised inside Anfield following the incident, with Atletico captain Koke also seeing yellow following a separate tangle with Mane.
BT Sport's refereeing expert Peter Walton said at half-time: 'The initial player Filipe could have gone for violent conduct.
'The referee sees that, Felipe in the meantime goes off, the referee gives him ample opportunity to come back, is that insulting and disrespectful to the referee?
'It’s either for the violent conduct or for the dissent at the end too. On reviewing the challenge again, it’s actually quite forceful – I wouldn’t be surprised if it was a result of the tackle.'
Former Liverpool forward Michael Owen said the challenge was 'in-between yellow and red', but says the referee changed his mind due to dissent.
Owen said: 'I didn’t like the look of the tackle but I did think the referee was going to give him a referee, until he didn’t walk towards him...'