LONDON - English champion Manchester City slumped to a third shock defeat in four Premier League games at Leicester on Wednesday to slip to third in the standings, seven points adrift of unbeaten leader Liverpool.

Just a few weeks ago City seemed unstoppable as it started its title defense with a 15-game unbeaten run.

However, a 2-0 reverse at Chelsea has sparked a run of three defeats in 18 days as Crystal Palace and Leicester both came from behind to hand Liverpool a huge advantage in the title race ahead of the Reds' trip to City on Jan 3.

Here, AFP Sports looks at what has caused City's sudden collapse:

Fernandinho blow

City coped admirably in Kevin De Bruyne's injury absence for most of the campaign thanks to its array of backup creative midfielders. However, it has badly missed Fernandinho's ability to play the more destructive role in the middle in the last two games.

The 33-year-old Brazilian had started every league game until Palace's visit on Saturday and is the one player in City's squad without a natural replacement.

Centerback John Stones deputized on the weekend, while the more attack-minded Ilkay Gundogan was deployed at the base of the midfield at Leicester.

"We have to try and find solutions. Ferna was not able to play because he's injured. We have to overcome this problem," said coach Pep Guardiola, who tried to sign Chelsea's Jorginho from Napoli in the summer as cover for Fernandinho.

"You have to think about how to solve it when you don't have players in a position."

Packed schedule

Even for a squad as deep as City's, English soccer's unique combination of a packed Christmas period and an extra cup competition can stretch resources.

Just eight days ago a strong City side beat a much-changed Leicester to reach the League Cup semifinals and stay alive in four competitions.

Leicester boss Claude Puel claimed victory on Wednesday was vindication for his much-criticized team selection in the cup tie, with the Foxes fresh to spring surprises over both Chelsea and City in the past five days.

As well as De Bruyne, Sergio Aguero didn't start against Chelsea or Palace due to injury, while David Silva has also been sidelined by injury in recent weeks.

Mendy missed

Leftback has also been a problem position, even as City enjoyed great success last season, due to Benjamin Mendy's knee troubles.

The Frenchman's return to fitness and form in the early weeks of the season promised to give City an extra dimension to its attacking play, but he has been sidelined again since early November.

Fabian Delph, a central midfielder by trade, has filled in at leftback, but is now facing a three-match suspension, including the Liverpool game, after being sent off late on at Leicester.

History lesson

Guardiola won three consecutive league titles at both Barcelona and Bayern Munich, but retaining the title in England has proved impossible for any team in the past decade.

A Manchester United side containing Cristiano Ronaldo and Wayne Rooney was the last to do it in 2008/09.

City's record haul of 100 points last term led many to believe it would buck that trend, but it is proving tougher than expected.

"Last season, everyone said it was so easy, but I know how difficult it was," insisted Guardiola.

"Last season we were so consistent and made a lot of points. They (Liverpool and second-place Tottenham) are both so consistent."

Mental fragility

The question remains whether a Guardiola side is capable of chasing down a title rival to win the league in the manner Alex Ferguson's Manchester United made routine in the 1990s.

In most of Guardiola's seven title triumphs, his Barca, Bayern and City sides have been well in front by this stage of the season.

Now they have to play catch-up and their lack of reaction to going behind to Chelsea, Palace and Leicester leaves City's mentality open to question.

"We are not happy but we try to overcome the situation. Seven points to Liverpool is starting to look like a lot," said City playmaker Bernardo Silva.

"We are not playing as well as we want. It's mathematically possible, but we have to be almost perfect from now."

Agence France - presse