Walter Mazzarri snubbed a handshake from Mark Hughes and blasted referee Bobby Madley's display after Watford's 1-0 defeat by Stoke.
Overworked official Madley gave 38 fouls - the most in any Premier League match this season - but missed a key one when Charlie Adam shoved Valon Behrami for the winning goal.
Even Adam admitted to Sky Sports: 'I think it was a foul actually, I pushed him,' after his header came back off a post and went in off Hornets goalkeeper Heurelho Gomes.
Mazzarri refused Hughes' handshake at the final whistle of a bad-tempered game in which his side collected five bookings - two of which resulted in Miguel Britos being sent off in the final minute.