In the last decade, only one side has successfully defended their Premier League title.

That was Manchester City in 2019, who had to muster 99 points to fend off Liverpool, who pushed them every step of the way.

It goes to highlight that retaining the title is not an easy feat, to the point where it has been even been suggested that it's tougher than winning the trophy on the first occasion.

That's without factoring in the mass of injuries that Liverpool have suffered, nor the COVID-19 restrictions that have robbed them of their supporters and created a jam-packed fixture schedule.

These are unprecedented times but Liverpool's struggles to maintain their extraordinary performance levels without key players is far from that.

Prior to Pep Guardiola's side retaining their league title, you had to go back to 2009 when Sir Alex Ferguson guided Manchester United to their third-successive triumph.

However, that was the last time United won successive titles under Ferguson following their collapse in the 2011/12 campaign that saw City oust them in sensational circumstances.

It was a campaign where Jonny Evans was forced to partner Rio Ferdinand after Nemanja Vidic damaged his ACL in December. Sound familiar?

Vidic missed the entirety of the campaign, whilst problems in midfield forced United to field their ninth midfield pairing by November.

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Manchester United's woes from a decade ago will act as little solace for Jurgen Klopp as he bids to address Liverpool's four-match losing run but it does highlight that they are not the first club to be unsettled by a spout of injuries to key personnel.

"There have been some changes in the team from the one that started the season," said Ferguson in 2011 when discussing the disruption to his side.

"You don't envisage having quite so many injuries.

"Everyone was fresh at the start. We had been through a brilliant pre-season in the States with not one injury. Then you are hit with a little list.

"It doesn't disrupt us to a great degree but it does unsettle the balance of the team.

"Sometimes we are having to rethink which team to play whereas when the team is in full flow you don't need to worry."