Manchester United fans have decried the lack of consistency in officiating after seeing Liverpool midfielder Wataru Endo escape a red card for a late tackle on Thursday night.
The Japan international was shown a yellow after catching Toulouse forward Thijs Dallinga on the top of the foot in the Reds' 3-2 Europa League defeat.
Some United fans felt aggrieved the 30-year-old did not receive a harsher penalty after comparing the challenge to the incident that saw Marcus Rashford sent off a day earlier.
The forward inadvertently clamped down on the ankle of Copenhagen's Elias Jelert in the Premier League side's crushing 4-3 defeat.