Manchester United have now conceded 29 goals in the Premier League this season, equalling their defensive record for the entirety of the 2017-18 campaign.
It has taken the Red Devils just 17 games to equal the tally, two games before the halfway mark, and it is the most they have conceded at this stage of a season since 1962-63
Jose Mourinho's side built a reputation for robust defending and being hard to break down on their way to a second-place finish last term, losing out only to Pep Guardiola's Manchester City.
Liverpool, who finished fourth last season, have now taken up United's position as the main challengers to champions City and moved back to the top of the league as they put three goals past the Red Devils on Sunday afternoon.
Sadio Mane gave Liverpool the lead at Anfield, although the visitors came back with a Jesse Lingard strike to make it 1-1 going into the break.
Two second-half goals from substitute Xherdan Shaqiri gave Jurgen Klopp's side a commanding lead, however, as Liverpool racked up an incredible 36 shots on goal as they cruised to victory.
United's defence did suffer a blow before kick-off when Chris Smalling, who signed a new contract on Saturday, suffered an injury in the warm-up and had to be replaced by Eric Bailly.
Bailly started in a back five for the Red Devils although Mourinho opted to switch to a back four in the second half, bringing on Marouane Fellaini for Diogo Dalot at the interval.
The manager was critical of his club's failure to sign a centre-back last summer as they saw efforts to secure the services of defenders like Harry Maguire and Jerome Boateng turned down.
Mourinho has reportedly made Napoli defender Kalidou Koulibaly his top target in January as he aims to shore up the Red Devils' problems at the back.
United have three games left before the window opens, as they travel to promoted Cardiff City next weekend before home games against Huddersfield and Bournemouth over the festive period.