Guus Hiddink accused Watford’s Juan Carlos Paredes of trying to get Diego Costa sent off after Chelsea were held to a goalless draw at Vicarage Road.
Watford right-back Paredes and Costa were involved in a petty exchange which saw both players booked by referee Mike Dean for their amateur dramatics.
Hiddink felt Paredes was trying to antagonise his short-tempered striker.
The Blues boss said: “It was very clear, because we were very close. It was just 10 yards from our bench.
“Paredes punched Diego in his back. After that they stumbled. Then Paredes brought his hands to his head and Diego was nowhere near his head.
“This is something we must not do. It’s provocation to get someone (sent) off the pitch. Happily the referee and the assistant referee saw it.”
Watford captain Troy Deeney took a dim view of the incident, too.
“It’s new-age football,” he said on BT Sport 1. “There’s a little touch and everyone’s rolling around. It’s just handbags. In Sunday League that wouldn’t happen because you’d be laughed at.
“I don’t like to see it, and we’ll have a word with Paredes on our side.”