The Newcastle United captain says old friends will become enemies on Friday night.
Lascelles will return to the City Ground for the first time since he finally left the East Midlands in the summer of 2015 when the Magpies come to visit.
Having come through Forest's youth academy, the centre-back stayed on loan for the 2014-15 season after signing with Newcastle in 2014.
After playing 66 times in total for Forest before his final departure, Lascelles has flourished on Tyneside and will be relishing the thought of returning to his former home.
However, he has insisted that there will be no lingering sentiment once he is out on the pitch, even going as far as to confirm that he will not think twice about celebrating if he scores against his former team.
Lascelles said, via Chronicle Live: "I have a lot of memories there. I was there from eight and they brought me through the ranks. I don’t know how they will take to me, boos or claps. If I score I am definitely celebrating.
"Obviously when I signed for Newcastle I was loaned back to Forest and they didn’t give me the greatest of times during that year - it was a strange year. I was a Newcastle player, but I was playing for my old club and that was hard to get my head around.
"It will be nice to go back. Some of the boys I played with are still there. We can be friends off the pitch but on it they are my enemy."
That pledge is unlikely to endear him to his former supporters, but all Lascelles will really care about is ensuring that Newcastle get back on track.