Millen, who moved with Holloway from Bloomfield Road to Selhurst Park just over a month ago, admits both sides will be looking to "get one over" on each other when Holloway's high-flying Palace host Blackpool.
But the assistant boss, who was only at the Tangerines for a short spell, hopes the Blackpool fans give Holloway a good reception in recognition of the three-and-a-half successful years he had at the club.
"He's very proud of what he achieved in the three years he was up there - it was the best journey Blackpool fans have ever been on, and that's the same with Ian," Millen told Advertiser Sport.
"That will never change, and I think just because on Saturday when we play against each other, the rivalry gets heightened, but deep down, I'm sure all Blackpool fans and players , and Ian himself, will all love the time they were together.
"I wasn't there as long as Ian but it's unbelievable how it turns around.
"We are looking forward to the game and it will be nice to see the players and the staff there.
"Obviously, Ian had a great time at the club and I hope the fans at Blackpool appreciate what he did there.
"I think the majority of them will but they're going to want to beat us and there's always that extra edge (of facing your former club).
"Ian will be desperate to get one over them and I'm sure Blackpool will be desperate to get one over Ian, so there will definitely be an edge to Saturday's game.
"Eventually you have to move on, and you do get the banter and the stick on match days but I'm sure everyone appreciates the great time they had in those three years especially."