It is supposed to be the calm before the storm, the period when hope is embraced and equality reigns, with alphabetical order shaping the Premier League table. But consider, for a moment, José Mourinho, Chelsea’s champion manager, and his issues over the past couple of weeks.

There has been sniping from him at some old adversaries, namely Arsène Wenger and Rafael Benítez, and an argument with Roberto Martínez at Everton over tapping-up claims regarding the defender John Stones. Mourinho must also contend with a thinnish senior squad – with few additions over the summer – and he has made his usual exhortations to his young players. They have to step up.

Then there is the recurring problem, and loud talking point, of Diego Costa’s hamstring. To Mourinho’s frustration, the striker is a doubt because of it for Chelsea’s opening fixture at home to Swansea City on Saturday. The club’s hopes of retaining the title feel directly linked to the condition of this muscle.

So, welcome back José and Chelsea, and the whole of the Premier League circus, although it really does not seem as though you have been away.

The sense of anticipation before the season is palpable andif the beauty of England’s showpiece sporting division is that any team can beat any other, then the title race, in particular, promises to be tight and richly entertaining.

It is difficult to look beyond the big four contenders – two from London and two from Manchester – but who will hold the trophy on 15 May, after 38 gruelling rounds, is not the sort of call that anybody can take to the bank.

Mourinho radiated his usual conviction at Cobham on Friday and the mind went back to his comment during Chelsea’s summer tour to North America. “You are speaking with the manager of the best team in England – we don’t have frailties,” Mourinho said. He was asked here how he felt on the eve of the season. “Confident,” he replied. “Always confident.”

Chelsea are the team to beat, or break down, because they have a brilliant goalkeeper in Thibaut Courtois and the meanest defence, which is protected by a remorselessly drilled midfield screen. Throw in the stardust further forward – most notably, last season’s Player of the Year, Eden Hazard – and it is a cocktail with a kick.

And yet Chelsea’s rivals, who trailed in eight or more points behind them last season, believe they can make inroads. Mourinho’s best XI has not changed and it was interesting to hear him admit that “if you stand still, you get worse. The old saying is right. It is dangerous.”

On the other hand, Mourinho was talking up the benefits of retaining a settled lineup, with players who enjoy instinctive understandings. “The biggest advantage,” he added, “is for them to think: ‘My club and my manager have shown that they trust me. Now, it’s my time to give that trust back.’”

No manager used fewer players than Mourinho in the league last season and it spoke volumes for the belief he has in his stalwarts and their durability (together, possibly, with his lack of faith in the club’s academy players). But Chelsea are not too many injuries from being stretched and the nightmare scenario would be if something happened to Hazard, whom Mourinho suggested was not given adequate protection by English referees, or if Costa’s hamstring held him back.

Another nightmare for Mourinho involves Petr Cech, the goalkeeper his club have sold to Arsenal for £10m. It was a decision taken by the owner, Roman Abramovich, out of respect for Cech’s wishes and Mourinho made it plain that he was against it. He now says he understands – Cech wanted to remain in London and had earned the right to his choice after 11 glorious seasons at Stamford Bridge – but Mourinho resembles a ticking time-bomb on this. If Cech does add the layer of stability that Arsenal need to turn them into champions, you can bet that Mourinho will go off.

Mourinho said “probability” dictated Arsenal had to win the league “some day”, and there is a tangible feelgood factor at the north London club which built steadily over the second half of last season, and climaxed in a second FA Cup triumph in two years.

Wenger continues to be evasive about his interest in the Real Madrid striker Karim Benzema but, if he were to end up getting him and playing him with Alexis Sánchez, Mesut Özil and Santi Cazorla, the expectation levels would soar. Regardless, Arsenal have to be considered as genuine contenders for the first time in a long time.

Manchester United have practically bought a new midfield in Bastian Schweinsteiger, Morgan Schneiderlin and Memphis Depay but Louis van Gaal continues to wonder whether he has sufficient creative class. After spending £230m in 12 months, the manager has a team closer to his image.

United are exciting, largely because they feel so unpredictable and Van Gaal is such blustering box office. He rode his luck at times last season and the Champions League play-off against Club Brugge promises to be pivotal. He knows there can be no excuses for failing to get closer to Chelsea.

Of the Manchester clubs, it is City who look the more convincing. Any team that cannot guarantee starting places to Samir Nasri, Jesús Navas, Wilfried Bony and Edin Dzeko must have something going for them up front – and one of those things is the £49m summer signing Raheem Sterling. The winger’s capture has weakened Liverpool, the only other club who may have a shot at the title, although their chances feel slim.

Mourinho spoke of there being five contenders but the certainty that four would be disappointed. He feels a smaller number of points will win it this time, because of the improvements to teams throughout the league. The battle is afoot. It will be fierce.