José Mourinho has confirmed Chelsea will offer John Terry a new contract in the new year to extend his senior career at Stamford Bridge into an 18th campaign, with the captain to follow Eden Hazard by committing his immediate future to the club.

“There are no doubts that he is going to get another contract,” said Mourinho. “I know that, he knows that. We in the club, in the board, we all know that and I think, also, you have to feel that. Without us confirming anything you have to feel that. He’s a very important player in the team so the next contract, sooner or later, will come. It’s a formality.”

Terry, who was outstanding playing his 645th game for the Premier League leaders in the 2-0 Boxing Day success over West Ham, had signed a one-year deal last summer; Chelsea have adopted a policy of offering only 12-month contract extensions to players in their 30s.

Yet the captain, who turned 34 at the start of this month, is an ever-present in the Premier League so far this season with Mourinho’s medical staff, in conjunction with the coaches, having devised specific training regimes to offer him the best opportunity to play regularly. Indeed, the defender was one of three players granted a three-day break from the club earlier this month to provide a breather.

The centre-half’s elite career had appeared to be drawing to a close when back and knee injuries restricted him to only 16 appearances over the six-month interim stewardship of Rafael Benítez, but he played in all but four of Chelsea’s league games last season and has maintained that eye-catching form this time round.

“He’s a happy guy, he’s playing well, he likes his team-mates, he likes the manager and he is working well,” said Mourinho, who has spoken often of his achievement in restoring the player’s “self-esteem” after those injuries prompted self-doubt in previous years. “It’s a very happy group and I think John feels very, very well.”

Chelsea, who face a potentially awkward trip to fourth-placed Southampton on Sunday, expect to announce Hazard’s new deal early next month. The contract will extend his stay to 2020 and, at around £200,000 a week, make him the highest-paid player at the club. Negotiations with the Belgian and his legal representatives – the player is currently without an agent – have been going on since the summer but all parties are convinced his future remains at Stamford Bridge.

The 23-year-old playmaker was excellent against West Ham, maintaining his own eye-catching form, and Mourinho is eager to tap into Hazard’s enthusiasm. “You see the way he plays: he’s a happy guy out on the pitch, he doesn’t feel the pressure, he doesn’t feel responsibility, he just wants to enjoy it,” said the Portuguese, who had sought to drum into Hazard the need to work harder defensively for the team last season.

“He plays in the first minute like he plays in minute 90. It doesn’t matter the result – fantastic, no pressure – and that’s a good feeling for me. Credit for him [for reacting to last season’s criticisms].

“He didn’t lose his spontaneity, he didn’t lose his happiness, he didn’t lose his creativity, none of his good qualities, but he won some other qualities. Even physically look at him, he’s a small guy but he’s very strong. He scored with his head [against Hull earlier this month], jumps well, he’s strong to hold off contact from opponents. We are doing all that progressively. We didn’t try to bring that out of him by flicking a switch. It’s progressive and great evolution.”

Chelsea, who have won all five of their fixtures in all competitions since losing for the only time to date this term, a 2-1 defeat at Newcastle on 6 December, do not anticipate any incoming transfers in January.

Likewise, having sold Juan Mata and David Luiz for £37.1m and £50m respectively in the past two windows with financial fair play in mind, they will resist any high-profile departures from the squad.

“I don’t think [there will be any],” added Mourinho. “Mata was a fantastic deal for the club. We couldn’t stop a fantastic deal for a club like ours that looks to numbers and must care about numbers, so it was an amazing number for us, so we had to do it.

“At that time we were just thinking about numbers. If he’d stayed in our team, our team would have been good and he would have been a valuable player and an important player for us. It was so important for us, but it allowed us to do other things. Like David [Luiz], a valuable player but amazing number, so good.”