Northampton manager Ian Sampson believes Peter Gilbert could come in for some harsh treatment when Southend come to Sixfields on Saturday.
Gilbert agreed a new deal with Sampson in May but delayed signing it and eventually joined the Shrimpers instead.
Sampson said: "It's history now.
"He's moved on, he's not a Northampton player anymore, he's a Southend player and we will look to get one over him as we would any other player.
"It's up to the fans what reception they give him.
"I'm not going to ask them not to give him a hard time - they are more than welcome."