Manchester City’s Premier League title defence appears over before Christmas, with Pep Guardiola’s men travelling to Arsenal on Sunday already 14 points adrift of runaway leaders Liverpool.

City have made the extraordinary routine, winning five of the past six major domestic trophies in England but have dropped as many points in 16 league games this season as in the whole of last season.

So what has gone wrong for a hugely talented and expensive squad under the tutelage of one of football’s greatest coaches?

Injuries to top players

Even a squad as rich in resources as City’s is not immune to injuries.

Leroy Sane and Aymeric Laporte suffered long-term knee injuries in the first few weeks of the season, with Laporte’s absence leaving a gaping hole at the heart of City’s defence.

Fernandinho has had to deputise out of position at centre-back, meaning the Brazilian’s influence at the base of City’s midfield has also been missed.

Manchester United cut their local rivals apart on the counter-attack in winning the derby at the Etihad 2-1 last weekend, while Norwich, Wolves and Liverpool have also exposed City’s frailties in defensive transition to inflict defeat on the champions.

Benjamin Mendy’s lack of fitness and an injury to Oleksandr Zinchenko has also led to a rotating cast at left-back, with none of the options available to Guardiola inspiring much confidence.

Even before Laporte’s injury, City appeared short at centre-back following the loss of captain Vincent Kompany, who left at the end of last season to take charge of Anderlecht.

Kompany’s final years at the club were ravaged by injury, but he played a vital role late last season as City won their final 14 league games to pip Liverpool to the title by one point.

The Belgian was an inspirational leader and his departure left City without a figurehead when things get tough.

Similarly, the issues at left-back were not unforeseen. Mendy has been blighted by injuries since he joined the club but City instead strengthened at right-back over the summer with the signing of Joao Cancelo.

Fourth-season fatigue

Guardiola is into his fourth season at City, matching his longest spell at one club.

The Catalan quit Barcelona after four seasons from 2008 to 2012 that left him burned out.

In explaining his decision, he suggested after winning 14 trophies in four seasons at the Camp Nou that the Barcelona players needed a new message.

Guardiola’s intense demands can also have a physically and mentally draining effect on players.

End of an era

A core of players was the constant in City’s most successful era but Kompany’s departure signalled a changing of the guard.

David Silva, 33, Sergio Aguero, 31, and Fernandinho, 34, have also been hugely influential, but are all beyond their prime.

Silva has already announced he will leave the club at the end of the season. Aguero, City’s all-time leading goalscorer, is out of contract in 18 months’ time.

City have put a succession plan in place for Fernandinho by signing Rodri for a club-record £62.8 million ($84 million) in July. However, the 23-year-old Spanish international has struggled as he adjusts to the rigours of the Premier League.

There is a local clamour for Phil Foden to be the long-term replacement for Silva and Gabriel Jesus has shared the striker’s role with Aguero under Guardiola.

But Kompany’s departure shows that transition will not be an easy one.

Liverpool charge

City have helped create a monster they are now struggling to compete with. Guardiola’s men re-wrote the history books by registering a century of points for the first time in the English top flight in 2017/18 and backed that up with 98 last season.

Liverpool’s tally of 97 was the third highest ever and yet still not enough to end the wait for a first league title on Merseyside since 1989/90.

In most other seasons, City’s return of 32 points from their opening 16 games would at least be enough to keep them in the running.

However, they have raised the bar and Liverpool have risen to the challenge. A relentless run of 15 wins and one draw from the European champions has seen them disappear over the horizon and surely out of reach.