Jonny Evans is now a Manchester United player for the second time after signing a short-term deal - with many believing he should have never been allowed to leave.
Evans was one of a number of United academy graduates to be given first team opportunities towards the end of Ferguson's time in charge.
He continued to feature under both David Moyes and Louis van Gaal, but the latter decided to sell him to West Brom in the summer of 2015.
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Evans would stay in the Premier League for a further eight years, starring for both the Baggies and Leicester, for whom he signed for in the summer of 2018.
He was released from his Foxes contract upon the side's relegation last season, and had been training with United at Carrington before the announcement on Monday that he had signed a short-term contract.
Evans played the second half of United's 1-0 win over Lyon in a pre-season friendly on Wednesday.
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He will also travel with the U21 squad for their pre-season training camp in the United States, and could feature for the first team in their friendly against Wrexham.
Now 35, Evans is still operating at Premier League standard, and although it is unlikely he would play any significant part for United if signed, manager Erik ten Hag could decide to keep him for the season.
That was a decision not taken by Van Gaal in 2015 - and it was a decision that shocked Ferguson at the time.
How Ferguson reacted to Jonny Evans sale
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Evans has collected 102 caps for the Northern Ireland national team, also acting as team captain.
Speaking to the Belfast Telegraph in 2017, then Northern Ireland boss Michael O'Neill - who was re-appointed to the role earlier this year - explained: "In September after last year's Euros, there was a conference in France for the coaches.
"Sir Alex was there talking about it and he openly said to me that he could not believe Van Gaal had sold Jonny Evans.
"Because having seen him coming through, he felt Jonny would spend his whole career at United or certainly to the latter stages of his career.
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"In the previous two years he had an injury, and at Man Utd they had Ferdinand and Vidic and then Jonny. There was a succession plan that didn't happen because of the change in manager."
The same outlet described Ferguson as being 'stunned' over Evans' departure - and he will surely be delighted that the defender is representing United once again.
Featured Image Credit: GettyTopics: Sir Alex Ferguson, Manchester United, Erik Ten Hag, Football