Newcastle boss Eddie Howe admitted he did not want to sell Elliot Anderson ahead of a meeting with the former Magpies midfielder on Sunday.
The 22-year-old Newcastle academy graduate was sold during the summer transfer window to Nottingham Forest, who host the Magpies in the Premier League this weekend.
Anderson has proved to be an impressive capture for Forest, who are third in the table, six points adrift of leaders Liverpool.
His departure came as part of Newcastle's compliance with profitability and sustainability rules (PSR), but Howe revealed the midfielder was a player he did not want to lose.
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"Elliot was a sale we didn't want to make," Howe said. "Nobody at the football club internally wanted to make that sale but we had to.
"I think that one is a very unusual place because I think that will be happening again, not just here but at other clubs where you're selling players for financial reasons.
"I don't think it's something that has really been done a lot in the history of the game unless you're under financial restrictions where you have to sell. A club that has financial backing but has to sell because of the rules, that's a new one."
Howe expressed further frustration at PSR rules and believes Newcastle were "incentivised" to sell Anderson.
"I think I've said before I don't understand that rationale - why we're in a position that you're incentivised to sell academy products," he added.
"I don't necessarily think they started with that intention of forcing teams to make those decisions.
"So for us to put all the work into Elliot, the academy, the coaches, the time, to then see him leave and now flourish for another Premier League club isn't something I think we should be in a position to do.
"It should be more of a level field, you can sell players and have the same effect that it was with Elliot. Of course it was all profit for us, his sale, that's why we were incentivised to sell him."
Sunday's trip to the City Ground sees Howe meet another familiar face in Chris Wood, who swapped the north east for Nottingham in January 2023.
The striker has flourished for Forest this season and is currently second in the Premier League goalscoring charts having bagged eight goals so far.
"I'm delighted for Chris on a personal level, because for me it was never lost how well he played for us," Howe said.
"He did everything but score, in terms of his positive performances were so important in our efforts to stay in the league, especially that first season when he joined.
"The work that he did, the unseen things. I think if you asked his teammates who played with him in that season, they'd say Chris was one of the reasons that we changed our position in the league and were able to win consistently.
"I'm delighted for him, great lad, great attitude, he had a really good time with us and pleased to see players go on and do well."
