Thorne spent some of his teenage years down on the south coast and has praised Pompey for his football upbringing as he prepares to face them.
However, it will be down to business this evening once the game kicks-off as the Rams look to progress to the next round of the competition.
“I really enjoyed my time at Portsmouth and it'll be nice to go back there,” he told the Derby Telegraph.
“We had a very good squad at the time and we probably underachieved a little bit.”
“Regardless of that, I enjoyed my time there and it helped me a lot football wise. Going there was my first real experience of senior league football.”
Is the League Cup a priority for Derby?
It will be interesting to see how many changes Derby boss Paul Clement makes for the game because of the arguably higher priority of the Championship.
In an ideal world, the league would be the only thing that the Rams have to focus on this season as they look to get promoted into the Premier League.
However, the League Cup shouldn’t be ignored because it represents the chance for the team to build some useful momentum and earn some extra revenue, which will be useful along the way.
If Thorne has a spring in his step for the game, should he feature, then that has the ability to rub off on other players, with a determination for the Rams to avoid an upset.