With none of his injured stars expected to return any time soon, Liverpool boss Jurgen Klopp has to decide whether to persist with three central defenders or revert back to the 4-3-3 system he has used -- largely to good effect -- for most of the season.
For the first time this campaign, the German started with a back three at Stoke City last weekend. Although his side won the game it would be a huge stretch to say that the system was a success. Despite the extra defender they had on the field, Liverpool looked as vulnerable at the back as ever. It's almost certainly not a long-term answer to Liverpool's defensive issues, but with a difficult trip to West Bromwich Albion coming up this Sunday, Klopp might well see it as a short-term necessity.
Liverpool have used a back three to good effect at times in the past, most notably when Roy Evans' side of the mid 1990s played some dazzling stuff and probably should have won at least one league title given the football they were capable of playing. That they never managed it was down to the weak mentality of the team rather than the formation they were playing.
Brendan Rodgers briefly experimented with a similar set up in 2014-15 and enjoyed some good results with it before eventually going back to what he was comfortable with. Ironically, one of the most impressive performers during that little run under Rodgers was Mamadou Sakho, and if the French defender hadn't fallen out with Klopp he would surely be a better alternative to the struggling Ragnar Klavan in the current set up.
While Sakho is rebuilding his reputation with some excellent displays on loan at Crystal Palace, Klavan has struggled of late. The Estonian was beaten too easily by Josh King for Bournemouth's equaliser in a 2-2 draw at Anfield last week, and was then given the runaround by Xherdan Shaqiri at Stoke three days later.
Nevertheless, if Klopp does persist with a back three then Klavan will most likely retain his place, if only for the balance he provides due to being left footed.
The system can be very effective but Liverpool's players are not used to playing it yet, and prior to the trip to Stoke they hadn't had any significant time on the training pitch to work on it. At least if Klopp employs it this weekend he will have had a week to prepare his players.
League leaders Chelsea play with three at the back every week, while second placed Spurs have used it to good effect on occasion this season as well.
It does take some getting used to though, particularly for the three centre-backs who are more impacted by the change than anyone else. Having an extra defender in there can sometimes lead to confusion and cause players to not take responsibility in the same way they would when playing in a back four, usually because they assume someone else will deal with the problem.
The change has not really worked so far for Liverpool but that's hardly surprising given the lack of time they've had to work on it.
Bournemouth grabbed a late equaliser after Klopp had switched to a back three and Stoke also found it easy enough to breach the reinforced rearguard last weekend when Jon Walters found himself all alone in the six-yard box. That was a classic example of the confusion you often see, as neither Joel Matip nor Dejan Lovren seemed to know where they should be positionally and the Stoke forward was left in a ridiculous amount of space.
But for the brilliance of goalkeeper Simon Mignolet, Stoke would have had another couple of goals and it's fair to say that Liverpool have not looked any more secure with three central defenders than they did with two.
It's a little surprising that Klopp has left it so late in the season to make such a significant change, but perhaps he feels as though injuries have forced his hand. Losing Jordan Henderson, Adam Lallana and Sadio Mane obviously hurts the Reds at both ends of the pitch. If it were only one or even two of them missing, Klopp could make do and mend, but with his attacking options now so depleted and his defensive screen Henderson unavailable, it appears as though he's decided to belatedly put more of an emphasis on tightening up at the back.
Klopp may have another reason for the tactical switch though, as both Stoke and this weekend's opponents West Brom have plenty of height in their side and pose problems from set pieces. By including an extra central defender, Klopp has been able to add some much-needed height to his team. With the likes of Emre Can and Divock Origi also in the side, Liverpool are suddenly a much more physically imposing side than they have been at various other times this season, where they have frequently been exposed by high balls into their box..
That, as much as anything, could be the reasoning behind Klopp's change in approach. The extra height and physicality playing with a third central defender provides could be vital in keeping West Brom at bay this weekend, as Tony Pulis' men are the set-piece kings and as Arsenal found out recently, they present the sternest test to teams who are seen as being vulnerable to the more direct approach.