Phil Neville has claimed that Chelsea's problems this season are purely down to the absence of Nemanja Matic, insisting that whoever gave the green light to sell him to Manchester United "needs sacking".
Red Devils boss Jose Mourinho recently admitted that he was surprised to land his top midfield target, who joined on a three-year contract in July for around £40m.
Matic has earned plenty of praise for his early showings in a United shirt, featuring in 15 of their games already this season, while Chelsea have yet to truly get going since his summer departure.
Speaking to BBC Sport, Neville said: "What's gone wrong for Chelsea? One word: Matic. It's as simple as that. The minute they sold Nemanja Matic was a mistake. When you had Matic sat in front of you, alongside [N'Golo] Kante, there was protection. Whoever made that decision needs sacking.
"That is one of the poorest decisions I have ever seen in the Premier League. If you ask any of those Chelsea players who they would want back, they would say Matic.
"Chelsea replaced him with someone who is going to do the same job – [Tiemoue] Bakayoko is not that player, he is not a holding midfield player. They didn't replace Matic. I wouldn't have let him out of the building, I would have chained him to the training ground walls."
Matic returns to Stamford Bridge for the first time as an opposition player next weekend, but he insists that he has 'nothing to prove' to his former suitors.