Liverpool's goalless draw against Manchester United has left them on their worst goalscoring run in the league in almost 16 years.

Jurgen Klopp's side have not found the net in their last three Premier League fixtures, their worst drought since March 2005, and have scored just one in four since lashing seven past Crystal Palace on December 19.

In those four matches they have had 63 shots, only 11 of which have been on target.

Here, the PA news agency looks at what has gone wrong and how Klopp might turn around their fortunes in front of goal.

Fabled front three have foundered

Despite some obvious success so far this season – Mohamed Salah, even with no goals in four games, is still the Premier League's leading scorer – Liverpool's world-class forward line are firing blanks. Sadio Mane's form has deserted him in the final third with just two goals in his last 13 league matches. Meanwhile Roberto Firmino's form has fallen off a cliff, with just six in his last 33 in the league, and he looks a player devoid of confidence. All the Reds boss can do is retain faith and work on the training ground.

Waiting game

The long-term absence of Virgil Van Dijk with a knee injury has robbed the team of the league's best defender but he was also an attacking outlet with his passing from the back. However, more critical at the moment is the unavailability of Diogo Jota, scorer of eight goals in 11 matches before a knee injury in the Champions League dead rubber against Midtjylland. Since then Liverpool have registered only two Premier League victories and scored 11 goals – seven of which came at Palace. Klopp has no back-up quality but Jota's return is not expected until the end of the month.

Changing formation

Liverpool's tried-and-tested 4-3-3 won them the Champions League and Premier League and only rarely has their manager deviated from it. One option of getting more goals into the team – outside of his four top forwards no player has more than one league goal – could be to switch to a 4-2-3-1. In his last two matches he has opted to have Thiago Alcantara as the pivot alongside the hard-working Georginio Wijnaldum plus one attack-minded midfielder. A switch to a double pivot, pushing Salah into the central striker role would open up wide a slot higher up the pitch.

Midfield shake-up

Injuries to all three senior centre-backs has hamstrung Klopp to the extent he has played two of his best midfielders Jordan Henderson and Fabinho in central defence for the last two league matches. Liverpool are missing the pair's quality, control and drive further forward but both cannot be released until Joel Matip is fully fit and Klopp can play either youngster Rhys Williams or the inexperienced Nat Phillips alongside him. It would also allow the Reds boss to move Thiago from his holding 'six' role to an 'eight' which would get him closer to goal more often.

Fix the full-backs

The roles of Andy Robertson and Trent Alexander-Arnold have been modified due to the nature of this unique season – without accounting for the loss of security given to them by them Van Dijk – and they are not bombing forward as much. Last season they contributed 25 assists between them, so far Robertson has five and Alexander-Arnold has two. The England right-back had Covid-19 at the start of the season and appears to have suffered the most, looking short of confidence.