Plymouth Albion boss Graham Dawe is against Cornish Pirates groundsharing with Plymouth Argyle for a prolonged period of time.
The Pirates are as they wait for a new stadium in Cornwall.
Pirates' Mennaye Field does not meet the minimum Premiership standards.
"If it ended up being past three or four or five games then it would be a problem," Dawe told BBC Devon.
Cornwall Council is discussing plans for a new £24m stadium, which the Pirates would share with Truro City Football Club.
Last month the Pirates announced they were in talks with Plymouth Argyle about playing Premiership matches at Home Park if they got promotion as they waited for the new stadium to be constructed.
"It would impact on our revenue streams," added Albion's chairman of rugby.
And Dawe says he would be unhappy to see another team play on a patch which belongs to his club.
"This club's been here for over 120-odd years and it's rightful to be here, you can't really hijack into the city from another area," he said.