Redruth scrum-half Greg Goodfellow has been banned for four weeks after being sent off for dissent in the first game of the season.
Goodfellow was dismissed in the 35-27 defeat by Cambridge after appearing to swear at referee Phil Watters.
But he decided to plead guilty to the charge of "match official abuse" at a disciplinary hearing on Tuesday.
Goodfellow, who was also ordered to pay £80 towards the cost of the hearing by Rugby Football Union judicial officer Christopher Quinlan QC, will miss the local derby against Launceston and games against Southend, Chinnor and Taunton.
He will be available to make his return against Bournemouth on 12 October.