Jurgen Klopp has worked wonders in the summer transfer window for Liverpool but the fact remains that he needs to make one more signing.
The German has largely focused his efforts on bringing attack-minded players to Anfield, with Sadio Mane and Georginio Wijnaldum arriving for a combined fee of roughly £60 million.
However, after watching his side almost blow a 4-1 lead against Arsenal at the Emirates Stadium, Klopp will have been made aware that weaknesses remain at the back.
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Indeed, Alberto Moreno was at fault for Theo Walcott's opener, whilst Alex Oxlade-Chamberlain was allowed to breeze past no less than three Liverpool defenders before firing past Simon Mignolet, courtesy of a slight deflection.
A new centre-back and left-back are needed at Anfield and it would seem Klopp has his sights set on a player who can play both roles.
According to the Mirror, Liverpool are weighing up a move for versatile Porto defender Bruno Martins Indi.
The Netherlands international, 24, is renowned for his strength and would represent an upgrade on the much-maligned Mamadou Sakho at the heart of defence.
Klopp might even consider playing Martins Indi over Moreno, whose mistakes continue to prove costly.
How much Liverpool would have to pay Porto for the Dutchman's services is unknown but, considering he cost a meagre £6.5 million two years ago, it's likely he would command a fee nearer £20 million.
Following his side's impressive victory over Arsenal, Klopp was typically mute about the prospect of making further signings but hinted that he will do so if required.
He said, per the Liverpool Echo: “We will see, actually I think we will try it with training and analyse things.
"I said before until August 31 why should I decide anything? We have time and injuries can always happen. But improvement, in my understanding, is about training and using the quality you have.
“We were far away today from showing our whole quality. A few nice signs, a few not so nice signs, that's all, let's carry on.”
Klopp will have been particularly frustrated by Moreno's performance against Arsenal after the Spaniard not only gave away a penalty, but was caught out of position when Walcott was slipped through to fire home in the first half.
Fans are calling for Moreno to be replaced but, unless Klopp finds a replacement, it's likely he will remain at left-back - at least until Joe Gomez returns from injury.