Jose Mourinho believes his former club Chelsea have left a "period of disappointment" and are "back on track" under coach Enzo Maresca.
The Portuguese manager, now in charge of Benfica, returns to Stamford Bridge for Tuesday's Champions League group game.
Under Maresca, Chelsea won the Conference League in his first season in charge and then lifted the Club World Cup this summer after upsetting Champions League winners Paris Saint-Germain in the final.
"From the outside, it looked like Chelsea [had] lost the identity as a club," Mourinho, 62, said in a news conference back at Stamford Bridge on Monday. "But what happened last season, it seems they are back on track. They gave trust to Enzo, he brought his ideas.
"The Conference League is an easy competition to win for a big club, I did it with Roma. The Club World Cup badge means a lot. Congratulations to them. I think that gives them a place of trust, of confidence.
"I live five minutes away from here, I feel it. My son comes to every game. There was a period of disappointment, a period of doubt, now it's one of happiness. I think Chelsea is back on track.
"It's more difficult to win the Champions League than the Club World Cup but Chelsea has the potential to do it."
Mourinho won three Premier League titles in two spells as Chelsea manager.
"Chelsea is a winning machine," he said. "I'm the biggest one until someone wins four [league titles]!"
"Benfica will be the fourth club I've come here with, it's a stadium where I won't feel any kind of antagonism, I think. But it wouldn't hurt me either. I can isolate myself without any problem.
"As they say, 'I'm not a Blue anymore.' I'm a Red [Benfica], and I want to win.
"Of course I will always be a Blue. I am part of their history and they are part of my history. I helped them become a bigger Chelsea and they helped me to become bigger at Chelsea.
"When I say I'm not a Blue I hope everyone understands that I'm speaking about the job that I have to do, that I have to do tomorrow.
"Before the game and after the game, it will be my Chelsea, but during the game, it will be my Benfica."
Photographs of Mourinho's successful spells at Chelsea are hung on the walls at Stamford Bridge and he was full of praise for his old club.
"There are not many clubs that do this because in many clubs there is a fear of what happened in the past," he said. "Sometimes it looks like they want to delete people who made history in the clubs. This shows that Chelsea is really a big club because big clubs are also about principles."
Mourinho, who rejoined Benfica less than one month after being sacked by Fenerbahce, also spoke of his excitement to be coaching in the Champions League again. He replaced Bruno Lage, who was fired after the club's opening Champions League defeat to Qarabag.
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"After 25 years I was expecting to go back to Portugal to [manage] the national team, not to Benfica," he said. "I left Fenerbahce a month ago without trophies, now I'm at Benfica and I'm very, very happy. It's a big responsibility, even for a guy like me with so many years of football.
"Having a European dimension doesn't mean thinking about winning the competition immediately; we're so far from that. Especially since it's just started. Thinking about it is bad for us. We're at a stage where every point is crucial We're in a more complicated situation because of the defeat at home to Qarabag, but we go into each game with the intention of getting points."
The enormity of the challenge is not lost on Mourinho with Benfica never recording victory over Chelsea.
"I don't get too hung up on those numbers," Mourinho added. "Normally, Portuguese teams don't have great results against the English because the English sides are strong. It's the pragmatism of it all. They have greater intensity, more useful playing time. Here, the level is higher in several parameters.
"But of course, I believe."