Things are not getting any better for Liverpool as a first defeat in an Anfield Merseyside derby since 1999 at the weekend only added to the sense their season is coming off the rails.

A fourth successive loss means they are on their worst Premier League run since 2002, a quartet of home league defeats is their worst run in more than a century and yet another injury ruling out a fifth centre-back option have left the defending champions stuck in something of a rut.

The Champions League win over RB Leipzig last week now looks like something of a blip in a downward trend which has seen them win just twice in 11 league matches since being top of the table at Christmas.

Most of the reasons for the decline are long-standing but the PA news agency’s Carl Markham looks at the current malaise and what can be done.

Things look bad. But how bad actually is it?

Well, it’s not great. Aside from the headline number of nine points from a possible 33, the contributory statistics add up to a whole lot of not much. In the last 11 matches there have been just two clean sheets and nine goals (six of which came in two back-to-back victories at Tottenham and West Ham in late January). Liverpool have scored in just five of those matches and have not found the net more than once in a match they have not won since mid-October.

So the forwards are to blame?

Yes and no. Mohamed Salah is still the Premier League’s leading scorer with 17 and his 24 in all competitions is one more than he managed last season. Sadio Mane, however, looks like he is starting to pay the price of playing for almost eight years without a proper extended break. He has just two league goals since Christmas, Roberto Firmino just one.

What’s the solution?

Diogo Jota, with eight goals in his previous 11 appearances before a knee injury in early December, is set to return to full training this week but how effective he will be after two months out remains to be seen. Unfortunately Divock Origi, with two goals (one in the Carabao Cup against League One Lincoln) in his last 40 appearances, stopped being the answer a long time ago.

A change of plan then?

Former England and Manchester United defender turned pundit Gary Neville said the players look like “zombies walking around thinking the same thing”. Manager Jurgen Klopp has rarely deviated from his preferred 4-3-3 system but he played 4-2-3-1 at Manchester City in November when he had all four forwards available. But with Firmino obviously struggling now could be the time to re-implement it with either Xherdan Shaqiri, Alex Oxlade-Chamberlain or both in attacking roles. The return to fitness of Naby Keita after two months also offers something different from midfield.

Will that be enough?

Well, there are obvious issues at the back which have not been resolved due to personnel continuing to get injured. Klopp has fielded 18 different centre-back pairings this season, 13 of which have started in the Premier League with a potential 14th coming this weekend if Nat Phillips replaces the injured Jordan Henderson to partner Ozan Kabak. And what of the ’emergency’ loan signing from Schalke? Kabak has played three games, been booked in all of them, and is understandably struggling to settle without a senior partner. The other deadline-day arrival Ben Davies has not featured in a matchday squad since February 3, which probably means he is not the solution either.