Chris Wilder accused referee Lee Mason of showing a lack of courage by not sending David Luiz off for a professional foul in Sheffield United's 2-1 defeat at Arsenal.
Luiz tugged Oliver Burke's shirt as the Blades winger tried to race clear after the Arsenal centre-back made an early mistake in the clash at Emirates Stadium on Sunday.
Arsenal's defender was not punished for the incident and the Gunners went on to secure three points courtesy of two goals in the space of three second-half minutes from Bukayo Saka and substitute Nicolas Pepe.
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David McGoldrick scored United's first top-flight goal of the season to set up a tense finale, but they were unable to prevent a fourth defeat out of four.