Merseyside Police are working closely with Italian police in a bid to stop a repeat of trouble which flared before Napoli played Liverpool in Italy.
Reds supporters were stabbed, chased and threatened ahead of the Europa League tie 12 days go.
There are fears some hardcore Napoli Ultras will be among the thousands of fans travelling to Anfield for Thursday's game.
Internet sites have suggested some Liverpool fans may look for revenge.
But Ch Supt Dave Lewis from the Merseyside Police football intelligence unit said he doubted that would happen.
"I don't expect the people who were involved in what happened in Naples to be coming over to Liverpool," he said.
"I really don't believe that they were genuine football supporters.
"We will have some fervent individuals who were following Napoli to be coming over here for Thursday night's game but that doesn't mean they are going to be trouble causers."