Former Birmingham boss Gary Rowett has revealed he turned down the chance to sign Victor Lindelof from Benfica because he was not "tough enough".
Lindelof, who joined Manchester United from Benfica in the summer, made his Old Trafford debut in the Carabao Cup against Burton Albion on Wednesday night.
Rowett, who is now manager of Derby County, was speaking to Sky Sports on when he revealed he nearly signed the central defender.
The Derby boss added, however, that when he and his backroom staff took a closer look they decided against pursuing a permanent move, as reported by the Dailymail.
Rowett said: "We had a look at him. It's ironic actually, I put it to the staff and some of them felt he wasn't quite tough enough.
"Then suddenly he's being touted around at £20-30m so I think we made a mistake.
"To be fair to him though, he got straight back into the Benfica team very quickly and of course went from strength to strength."
The 23-year-old joined Manchester United in the summer for £39.5m from Benfica, but the defender has failed to nail down a regular starting place for Jose Mourinho so far this season.
During his time at Birmingham, Rowett - who currently manages Derby - said he was approached by an agent who offered the services of the Swedish defender to the Blues.
"About two or three years ago when we first went into Birmingham, an agent called us and said Benfica were trying to get some of the younger players out to expose them to different levels," Rowett said, speaking to Sky Sports.
Lindelof made his Manchester United debut in the Uefa Super Cup defeat against Real Madrid, but failed to make an impression. He was then left out of the first three Premier League matchday squads, with United manager Jose Mourinho saying the defender needed time to settle in.
Lindelof then partnered Chris Smalling at the heart of United's defence in the Champions League win over Basel, with regulars Phil Jones and Eric Bailly missing the tie through suspension.