Serbia international Matic, 25 ,left the Blues in 2011 as a makeweight in the deal that brought Brazilian David Luiz to west London, but after two years with Benfica, Chelsea look ready to bring him back for a second stint at the club, with the midfielder telling Portuguese media he has played his last game at Estadio da Luz.
In Belgian Hazard, however, Mourinho is confident Chelsea bought a player of undoubted potential with their £32million deal from Lille last summer and the 23-year-old scoring 11 goals so far in an impressive campaign.
Speaking to the London Evening Standard, Mourinho said: "Eden can become one of the best players in the world. Now he sees his football and profession with different eyes.
"He understood how there is a gap between the talent and the performance and a gap between the occasional performance and the permanent stability at a high level. He now understands how he can fill this gap.
"He trains much better, he concentrates much better. Tactically, he has had a big evolution. He understands how to put his qualities on the surface of the team. He understands the best way to hide his weaknesses.
"He is 23 and now in his second season in England after an experience in France. He is playing in a Chelsea side trying to win the Premier League, also the Champions League, and is going to the World Cup with Belgium. He has in his hands all the tools to fill these gaps.
"Everyone knows he is a talented player, that he was that when he arrived here. But now he is trying to go to a different level, we are helping him and he is doing it step by step. Hopefully, the big talent can transform himself into the big player."
In a wide-ranging interview, Mourinho also gave his thoughts on the prospects of beating Manchester City to the Barclays Premier League title, which he claimed would be "my greatest achievement" because of Manuel Pellegrini's squad - who currently trail leaders Arsenal by a point - being "in another dimension" to their rivals due to the spending power at the Etihad Stadium.
Mourinho also suggested Manchester United manager David Moyes was not under pressure from anyone other than the media following a testing transition after taking over from Sir Alex Ferguson, and that while the Red Devils were perhaps too far off the pace to mount a challenge for the 2014 title, Moyes would "achieve success sooner rather than later".
Key to Chelsea's hopes of securing success for themselves this season could well depend on how much business Mourinho can push through this month.
Confirmation of Matic's transfer is expected imminently after the midfielder told Portuguese newspaper A Bola he will not be wearing the Benfica shirt again this season.
"I have played my last game here," Matic said.
"I want to thank all the people at the club and all the supporters. Benfica will forever be in my heart.
"I played here for two and a half years. I gave my best in every training session, every match, and now is the right time to leave.
"I want to improve, I want to go to a better league and I want to go to Chelsea, the club which I also love."
Matic also revealed the Lisbon side have tried everything to persuade him to stay, but his mind is firmly made up to return to Chelsea.
"The Benfica president did everything he could to get me to stay here but I have wanted to leave and insisted on leaving," said the Serbian.
"I respect the effort made to keep me at the club, everyone at Benfica has been very good to me and made me very happy, but I reiterate that I insisted on going as the time is right."