Time for Reds to ZONE out? IT'S THE DEBATE THAT WON'T GO AWAY - A BIT LIKE THE REDS' SET-PIECE FAILURES.
T'S a debate that feels as old as time.
It's been on the Liverpool agenda before, and it is certainly on the agenda again now, following the Reds' balloon-bursting defeat at home to Crystal Palace on Sunday.
Set-pieces. Marking. Zones. To mark or not to mark? Mark the man, or mark the space? You'll surely remember the discussion from Rafa Benitez's time at Anfield, when it seemed that each week there would be a detailed dissection of the Spaniard's defensive system, peppered with quotes from ex-professionals about 'accountability' and how 'space never scored a goal.'.
It infuriated some, not least Benitez, who swore by the system and believed the numbers backed up his faith in it.
But it's back on the radar now. Christian Benteke's winner for Palace was the 17th goal Liverpool have shipped from 'dead balls' this season - though that figure does include four penalties and two direct free-kicks.
"I don't know how often we spoke about set-pieces but we cannot speak about defending setpieces," Jurgen Klopp said after the game.
If only it were that simple. So here, we take a look inside the great zonal marking debate.
What is zonal marking? Zonal marking works on the principal of players covering space at set-pieces, rather than picking up specific men.
Usually, the defending team starts with a line of defenders across the sixyard line, with the rest stationed between there and the edge of the penalty area.
The job of the men on the six-yard line is to attack the ball if it is delivered into their 'zone', while the others are tasked with blocking runners and positioning themselves to deal with any second balls which may arise.
There is usually a man positioned ahead of the front post to attack anything there - Steven Gerrard performed that role particularly well for Liverpool for a number of years - while some teams will also station men on the far post to clear anything that gets past the goalkeeper there.
Why do teams do it? The aim at a set-piece, whether zonal marking or man-to-man, is the same.
Win the first ball. Win the second, if necessary, and clear the danger.
Advocates of zonal marking believe that the best way to do that is to place your best headers of the ball in the most dangerous positions (zones). Man-toman systems risk seeing those players dragged out of position, away from the danger area centrally in front of goal. A defender man-marking can take his eyes off the ball to look at his man, a cardinal sin at any level. That shouldn't happen with a zonal system.
Zonal marking fosters collective responsibility, and can also enable teams who perhaps do not have an abundance of tall or powerful players to find a way to defend set-plays effectively, using more creative methods.
It is also something that, in theory at least, can be worked on relentlessly and improved on a training ground. You can't make a player taller at Melwood.
Additionally, the exaggerated spotlight on shirt-pulling and holding in the penalty area makes man-to-man marking an increasingly risky strategy.
Why do some people hate it? There is certainly plenty of hostility towards zonal marking, particularly among ex-pros. Doubters complain that attackers are able to get a free run to attack the ball in a zonal system, with defenders left with a standing jump.
Others argue that the system creates grey areas, vacuums of responsibility. With a man-marking system, you know which player has lost his man. That's important, apparently.
Another argument against zonal marking is that it requires players to make instinctive in-game decisions. It requires communication, leadership and lots of organisation, plus a little bit of luck.
What do the experts say? Jamie Carragher: "The man on the street, the supporter, he wants two on the post, one up front, two on the edge, everyone marked and someone on the front space. You need 14 players! There's for and against for both of them but this is the problem with man marking, people don't watch the ball.
Gary Neville: "I'm not a fan of zonal marking because what you're asking for is instinctive thinking at different moments in the match depending on where people stand.
"You're asking players to think for themselves and make decisions.
"You talk about leaders, people who can command and organise the box. We know there's a lack of them."
What about Liverpool? Earlier in the season, Jurgen Klopp went on Sky Sports' Monday Night Football to talk about his team.
It was after a game at Swansea in which Liverpool had come back to win having conceded early from a set-piece.
Klopp, inevitably, was asked about his set-up at corners and free-kicks.
"It's not good," he said. "When I came in we had to change a few things, formations and things in set-pieces.
"When you play against West Brom, Crystal Palace, West Ham last year, (they are) unbelievably strong.
"It's not about the formation, it is how we react in the moment."
Klopp outlined five players who operate in a 'zone' at corners, plus a sixth if there is no man to specifically pick up at the far post.
He also discussed the need for players to block off runners from deep, stopping them before they get the chance to meet the ball.
"Sometimes goals come from a loss of concentration," he said. "You need to be orientated all the time.
"There is no solution. We do not have the tallest team, but we need to find a more creative solution.
"We have played man marking because we had a lot of tall players, who could win the challenge.
"But other times we have had to find the solution."
Clearly, given recent woes from corners, free-kicks and even long throws, they are still searching for that solution.
It can be worked on relentlessly and improved on a training ground. You can't make a player taller at Melwood.
Jurgen Kopp watches his side go down to Crystal Palace on Sunday and (left) dissecting Liverpool's defensive issues on Sky's Monday Night Football with Jamie Carragher earlier in the season ANDREW POWELL/ LFC/GETTY