English FA Premier League:A freezing December's day in the Surrey countryside. Petr Cech is delayed for an hour by drug testers at Chelsea's training ground and is full of apologies, rubbing his hands together to warm them up before offering the kind of handshake that brings back memories of the old Carling advert and Len Ganley crunching a snooker ball into dust.

We have arranged to meet at the Woodlands in Cobham (the sort of hotel where even the porters wear Prada) and the Rotary Club parties are already under way as the Chelsea goalkeeper takes his seat beneath a giant Christmas tree.

"This is the kind of weather when it's nice that I have my headguard," he explains. "Every other goalkeeper is freezing, but me? My ears are nice and warm."

"Mr Zero", as he is known in the Chelsea dressingroom, is on good form, generous with his time and happy to talk even long after the tape has stopped recording. These are exciting times for the world's best goalkeeper. In his personal life, he and his wife, Martina, are expecting their first child in January while in a professional capacity, he is delighted to report that Chelsea have reinvented themselves as title challengers.

"I think some people thought we would never recover when there was a change of manager," he says. "When Jose left it was really difficult for everyone because we had had three years together and enjoyed so much success. The relationship between him and the players was great and then, suddenly, there was this big announcement. Sometimes you can see it coming, but this one? Nobody saw it coming. It came out of nowhere.

"But I'll tell you what I really like - all the players have pulled in the same direction, everyone has stuck together and, in a difficult time, we have turned everything around. I hear players at other clubs talking about 'having great team spirit' but never actually proving it when it matters. The time to prove it is when things are difficult and this is what pleases me.

"We will never forget what Jose did but we knew we had to go forward rather than feeling down and depressed. We had to turn the next page."

A lot of the credit, he says, should go to Avram Grant: "The important thing is that he had the respect of everyone from day one. You can be the best manager in the world but if the players don't trust you it will never work. He had that respect. Plus he is a clever man. Sure, he is modifying a few things but, essentially, everything is the same as before because he knew we already had a successful structure."

Cech has never hidden his disappointment about Mourinho's departure - "sad" and "surprised" are adjectives he uses - but he believes outsiders have underestimated the strength of character within Stamford Bridge. This is his fourth season at the club and he tells a story about Roman Abramovich to give an insight into life in SW6.

"It was when I was recovering from my head injury," he says. "I think this period of my life was actually much worse for Martina because she was with me every second and saw close-up how it affected me. I couldn't read for more than five minutes without falling asleep. I had terrible headaches and I was taking a lot of medication. I would sleep for almost all of the day . . .

"Everyone at the club sent messages to Martina as well as me but what really impressed was the owner was in touch almost every day, texting her to wish her well and check how I was doing. It was not just Roman Abramovich who showed this warm, personal side but I think it says something that he wanted to be involved . . . Maybe from the outside, people don't see how close everyone is at Chelsea. They don't understand the spirit at our club. But inside, we know."

Cech's own strength of resolve is typical of what it takes to reach the top of his profession.

"Consistency" is a word he uses about a dozen times in half an hour, which will come as no surprise to anyone familiar with the way he obsessively accumulates clean sheets.

At 25, still maybe five years from his peak, he already deserves to be recognised as the best in the business. Some Italians might dispute that, but not even Gianluigi Buffon has a personal best of keeping 25 clean sheets in one season or going 1,025 minutes without conceding.

Then, of course, there is the way Cech has swatted away every personal crisis. In his second season at Chelsea, for example, he helped the team defend their title despite keeping a secret from the public.

"I started having a problem with my left shoulder and it got really bad," he recalls. "I had basically broken my shoulder but I thought I could get through so I carried on. Then, in the middle of that season, I broke my other shoulder so from December to the end of the season I had to play with two broken shoulders . . . it was really difficult."

A goalkeeper playing with two broken shoulders? It sounds too bizarre to be true. Yet Cech, lest it be forgotten, came back from his brain surgery within three months of his collision with Reading's Stephen Hunt last season.

The specialists, he says, have just told him he will have to continue wearing his protective headgear for at least another 18 months. "It's no problem in December," he says. "It's when it's hot that I wish I could be like everybody else."

• Guardian Service