Great full-backs are a rare commodity in modern football. Héctor Bellerín at Arsenal in the last 12 months has gone from one of the best, to a substitute, to a Barcelona transfer target and back into Arsène Wenger's plans.
However, over at Paris Saint-Germain, the French club seem to be stockpiling defenders, waiting for a full-back apocalypse.
Veteran left-back Maxwell has retired, but PSG were quick to act, signing Yuri Berichiche from Real Sociedad to compete with Layvin Kurzawa for the starting spot.
On the right-hand side, there was already competition for places as Manchester United transfer target, Serge Aurier, fought with Thomas Meunier for the starting role.
The Ivorian was picked 21 times in Ligue 1, with the Belgian just three behind on 18, but that is now irrelevant since the club confirmed the free signing of Dani Alves.
Although he is 34 years old, the Brazilian is one of the best in his position and proved that with a stellar campaign in Italy, helping Juventus reach the final of the UEFA Champions League.
PSG hope his influence and experience will spark the same fate at the Parc des Princes and take them beyond the quarter-finals for the first time.
As the Parisians looks to try and gather funds in anticipation for a £196million move for Neymar, Aurier, being the most profitable out of the two remaining right-backs, looks like being allowed to leave this summer.
Monaco are playing hard-ball and after trying to sign central midfielder – cum-right-back – Fabinho, The Independent report that José Mourinho has now turned his attentions to Aurier.
The defender could arrive at Old Trafford for just £25million, which seems like a bargain during a window where rivals Manchester City look set to spend £130million on three full-backs.
Antonio Valencia signed an extension to his deal in May, keeping him at United until 2019 with the option of an extra year. However, he is 31 years old and is not a natural in the role.
He enjoyed a great season under Mourinho, but Aurier would be an upgrade defensively, while also providing an attacking threat. The Ivorian has a bright future ahead and the Portuguese boss could be the man to pull the best out of him.
Who is Serge Aurier?
After breaking through at RC Lens as a teenager beside former Manchester United target, Raphaël Varane. The French-born, Ivory Coast international would spend three seasons at Toulouse FC and establish himself as a tremendous physical specimen.
Able to play at the right of a three-man central defence and as a right wing-back, he demonstrated that he was as good in defence as he was going forward.
Blistering pace, able to deliver quick deadly balls into the box. His strength and aerial presence has seen him fill in at centre-back without missing a step.
During the 2012/13 campaign, Aurier not only contributed six assists, but he added six goals, his best goal-scoring season to date.
It was after that year that, despite being an Arsenal transfer target, PSG made their move. Originally signing the right-back to a one-year loan deal with an option to buy him for €10million. His debut season wasn’t as eye-catching as hoped, but there was no way they were going to turn down an opportunity to sign Aurier.
“Now I know the squad, it's different,” Aurier said in the summer of 2015.“I can start next season on solid foundations. The aim is to work and be well physically.
“I have the quality to do something big here. I'm in a locker room with big players and I have to put myself forward.
“I'm not happy with my last season but I know myself that I can do better and earn more game time than last year.”
Aurier’s off the field problems
The Ivorian was enjoying a good campaign, playing 19 games up until February, but then Aurier imploded.
Broadcasting live with a friend on the social media platform Periscope. For over 90 minutes, the PSG player answered questions from fans. Almost instantly, he realised what he had done, removing the video, but the damage was irreversible.
Aurier called then manager Laurent Blanc a ‘homosexual’, he also insulted goalkeeper Salvatore Sirigu, defender and fellow right-back Gregory van der Wiel and the abilities of goal-scoring forward, Edinson Cavani.
He eventually apologised for his actions, admitted he made a ‘stupid mistake’.
Obviously a troubled individual and someone that you would be wary of signing, but it’s his on the field actions that have kept PSG from selling him. They know his worth and won’t let these incidents get in the way of a very talented player.
How Aurier has developed at PSG
One of the defender’s biggest weaknesses was his eagerness to fly into slide tackles. Quite often he’d miss and either foul or leave his side exposed.
Last term he was attempting 5.3 tackles per 90 minutes, winning 4, now he’s reduced that to 2.9 attempts, but winning a higher percentage at 2.4 per 90. That's an increase from 75 per cent, to 82.7 per cent. A superb improvement over just one campaign.
He was being dribbled past 1.3 times per 90 minutes, but that has now come down to 0.5. He’s finally showing maturity, both on and off the pitch. That is backed up with his fouls reducing from 1.7 to just 0.9 per 90.
It seems unthinkable that Aurier is actually making more crosses this season than he did last, going from 3.7 attempts to 5.4, improving from two assists to three last season.
All this development has come with Meunier challenging the Ivorian for minutes in the first-team. The Belgian finished with 18 starts and he is the reason that PSG could be convinced to sell Aurier this summer.
Moving away from the French capital could be the best move for everyone. PSG know he is a valuable asset and would be able to make a profit on him.
Although a deal for £25million seems cheap in the current market, when you factor in the defender's murky past and that clubs know PSG have to sell with three quality right-backs on the books, they are not in a position of power.
It's a fee that would be easy for Manchester United to reach, especially if they were willing to go up to £40million for Fabinho. His defending could use some fine-tuning, it’s still better than your average defender in the top flight and he’d be an explosive addition down the flanks.
Then it would be up to ‘the Great One’ to work on making him a better person and a more rounded player.