Brendan Rodgers and Jamie Carragher believe conceding from set-pieces is a big part of Liverpool's problems this season.
Manchester United became the seventh team to score from a set-piece situation against Liverpool as a Wayne Rooney goal handed Louis van Gaal's men a 1-0 victory on Super Sunday at Anfield.
The hosts allowed substitute Juan Mata to find Marouane Fellaini in the area and although his header struck the bar the ball fell to Rooney, who made no mistake.
Liverpool have conceded more goals by that means than any other Premier League team this season - a statistic that Carragher called "alarming."
As the ball came into the box against United, Liverpool boss Jurgen Klopp had three men marking zonally and five man-marking United players, including Jordan Henderson who was supposed to be picking up Fellaini.
Carragher asked former Liverpool boss Rodgers on Monday Night Football, what type of marking from corners does he thinks works better.
He replied: "My preference is for man-to-man marking.
"Normally the opponent will send five players into the box - normally one in front of the goalkeeper and four attacking the ball, splitting their runs into various areas. My preference is to have players marking those four and have one marking the guy around the goalkeeper.
"When you're conceding goals - and as Jurgen Klopp can see, Liverpool are conceding goals far too easily - you have to intervene at some point. If you've got players being beaten one-on-one in a duel too easily then you have to find a different way - usually switching from man-to-man to zonal defending to try and help the team."
When analysing Rooney's winning goal Sky Sports pundit Graeme Souness, who was in the studio on Super Sunday, believed one of the main defensive errors made by Liverpool was substitute Jordon Ibe's inability react quick enough to close down the short corner from which Rooney scored from.
United developed a two-against-one situation and Ibe was slow to close down Mata, whose cross was met by Fellaini.
However, Rodgers, who gave Ibe his debut for Liverpool, refused to criticise his former player.
Rodgers said: "In fairness to Jordon Ibe, it was just a little bit of inexperience. Everyone can see he's super quick. He's gone out and all of the other corners, they didn't play short. So maybe he was thinking that Man Utd wouldn't play it short and it was going to come in to the box.
"It was just his distance and he'll get that through experience. The players coming on need to be concentrating on the side of the field - you've got to be focused in while watching the game on what your job is and when the manager takes through your role for set-pieces, it's vitally important you know what your job is, so your team can make the adjustment."