The Reds goalkeeper came charging out with the former Manchester United attacker through on goal and wildly hacked him down with a high challenge.
Although Diouf had the goal gaping, referee Martin Atkinson decided that the incident only warranted a yellow card – a move that infuriated Stoke boss Mark Hughes on the touchline.
Stoke’s official Twitter account was under no illusions at what the colour of the card should have been.
39' Mignolet comes out of his area, fouling Diouf. Yellow card given, he's last man! Should be red! (0-1) #SCFC
— Stoke City FC (@stokecity) November 29, 2017
They wrote: ‘Mignolet comes out of his area, fouling Diouf. Yellow card given, he’s last man! Should be red!’
No doubt Hughes will have plenty to say after the match about that one.
Stoke were also incensed at Sadio Mane’s goal, claiming that Joe Gomez had taken the ball out of play.
While the Liverpool man seemed to keep it in on that occasion, Stoke fans have every right to be annoyed at Mignolet still being on the pitch in the second half.