Nemanja Matic
Matic re-joined Chelsea in January 2014 and has been vital to the club's title challenge.Getty Images

Chelsea manager Jose Mourinho says Nemanja Matic's move back to Stamford Bridge in the 2014 summer transfer window has signalled the start of a new era in how the club deal with the departure of their young players.

Matic re-joined the Blues for a reported £21m, two years on from being a makeweight in the deal which saw David Luiz move to the Premier League club from Benfica; a deal sanctioned by then manager Carlo Ancelotti.

The Serbian midfielder has been key to Chelsea's surge to the top of the Premier League this season operating at the base of the midfield behind marquee summer signings Diego Costa and Cesc Fabregas, and Mourinho says the arrival has changed transfer operations at the club.

"If I was here a left-footed player – 1.95m tall, a midfielder – would never, never, never leave. Never," Mourinho said ahead of the Champions League last 16 second leg against PSG which sees Matic return after being suspended for the match against Tottenham and West Ham.

"I think now I brought also a little bit of my experience," he added. "Not just as a coach, also at a business level. I think [with players] at these [young] ages it is good for the 'father club' to be protected because at these ages sometimes the evolution of the players, is sometimes good and sometimes bad. It is important to keep control of the situation.

"These days, when you have a player, you can loan him or sell him but you have ways of being in control of his future. At the same time I think Chelsea were brave by bringing [Matic] back. If in this world you want to do the best for your club, you don't protect yourself from possible critics. You simply do what you think is the best.

"And at that time we wanted a midfield player. We had three or four but the best one was a former Chelsea player. Chelsea were brave to say, 'We are sure this is the right one. We are sure he is going to be a success here.' No critic will be stronger than that. Of course, we read a few comments but this is part of the business.

"Probably in the future, the next time Chelsea does a deal with a young player then Chelsea will keep control. Another aspect of that is also the fact that Chelsea had so many first-team managers in these years. It is difficult for the club's board to have a certain philosophy on the table, to have a philosophy is much easier for our board."