Jose Mourinho says that Chelsea sanctioning the sale of Nemanja Matic suggests something unusual has taken place behind the scenes at Stamford Bridge.
Manchester United signed Matic from the Premier League champions for a reported fee of £40million and the Serbian midfielder impressed in his Old Trafford debut on Sunday, as the Red Devils thrashed West Ham 4-0 to top the table at the end of the opening weekend of the new season.
Chelsea manager Antonio Conte is reportedly unhappy at the departure of Matic and Mourinho has expressed his surprise that a transfer was possible.
"[It] depends on what was happening behind [closed] doors," he said.
"And we don't know. The only thing we know, of course with Chelsea money, I brought him to Stamford Bridge because I thought he was a player with special qualities.
"And since I left I always thought he could be a perfect player for us. But I didn't disturb him. I didn't disturb Chelsea. I never thought it was possible unless something special was happening.
"And it looked like something was happening. Because his agent told me 'you can have him, you just have to pay'.
"So we have him, and we are very happy with that.
"Because he's a player that our team needs and now with these kind of qualities we have Nemanja and Michael Carrick. Michael in spite of his age has a role to play. And I'm happy with these kind of stability players."
Another of United's off-season recruits, Swedish centre-back Victor Lindelof, was left out of the matchday squad after struggling in the UEFA Super Cup loss to Real Madrid.
And Mourinho feels the 23-year-old must be allowed to adapt to English football following his arrival from Benfica.
"I think Real Madrid was too early for him," he said.
"He played because [Phil] Jones and [Eric] Bailly were both suspended. I had players coming from different leagues to the Premier League [in the past] and normally it is not easy.
"I brought in 2004 a phenomenal central defender to England, Ricardo Carvalho. He was one of the best central defenders in the last decade in the Premier League but he struggled.
"It was difficult for him to come and adapt in the beginning.
"I think Victor needs a little bit of time. And he's going to have that time. Let's go step by step, because Victor is a fantastic player."