Jose Mourinho turned down the chance to bring Eliaquim Mangala to Chelsea in January because of the high price tag, reports The Evening Standard.
The Chelsea boss instead opted to buy Kurt Zouma for £12 million. The 19-year-old was then loaned back to his club St Etienne for the rest of the season before joining up with his Chelsea team-mates in the summer.
Mangala eventually left Porto for the Premier League in August, joining Chelsea's main title rivals Manchester City in a £32 million deal. Having put in an imperious performance against the team that rejected him last weekend, Mourinho's rejection could be one he lives to regret.
However, although the reason Mourinho chose Zouma over Mangala is not stated, it is likely Chelsea had to opt for the former in order to comply with Uefa's financial fair play regulations. Mourinho's choice saved Roman Abramovich £21 million.
Zouma is yet to make his debut for the Blues but is set to play a part in Wednesday's Capital One Cup encounter against Bolton Wanderers. Meanwhile, Mangala announced himself on the scene against Chelsea last weekend, keeping Diego Costa in his back pocket.
Mangala's seamless introduction and towering presence has already been touted to be part of the next great defensive partnership alongside City skipper Vincent Kompany. Despite is high price tag, his debut has given Manuel Pellegrini plenty of encouragement that he will eventually be considered good value.
Mangala arrived at the Etihad with no experience in a top five league, earning his reputation with Porto. Zouma impressed in Ligue 1 but comes to Chelsea with much more to prove.
However, the youngster, who has played with Mangala for France's Under-21 team, is hoping to break his way into Mourinho's first team plans by impressing against Championship outfit Bolton on Wednesday.
There is concern that Zouma is not quite ready for the trials and tribulations of the Premier League and the pressure is certainly on from Mourinho. Having made mistakes in pre-season, the Special One considered buying a more experienced defender to strengthen the squad.
A fresh loan move was also on the cards for Zouma. He stayed put and the player could not be happier to be in west London. He says his time spent with idol John Terry will help his career progress quicker.
He told the same report: “My favourite footballers as a kid were John Terry and Mamadou Sakho, now of Liverpool. Terry is a great leader and the perfect example to young players. It is very exciting for me.
"I’ve always looked up to him and I just want to learn as much as possible from him. I speak to him and he’s a very nice man.”