David de Gea has been of Manchester United’s greatest ever goalkeepers and was undoubtedly the club’s best signing of the last decade, but his form has faltered in recent times.

After signing from Athletico Madrid in 2011 the Spaniard took some time to adapt to the physicality of English football, with many questioning his ability to deal with aerial balls into the box.

But former United boss Sir Alex Ferguson persevered with his young ‘keeper, and gradually de Gea began to establish himself as one of the best shot-stoppers in the league.

By the start 2014-15 campaign, de Gea was almost undisputedly the best goalkeeper in the Premier League and held a firm grasp on that title until last year.

But as the likes of Allisson and Ederson put in faultless performances week on week, the mistakes that de Gea had all but eradicated from his game in the past has begun to become worryingly frequent now.

The theme has continued into this season, and culminated in some abysmal showings over the festive period from the 29-year-old – de Gea fumbled a mishit shot from Ismaila Sarr to gift Watford their first goal in a 2-0 defeat, and a dreadful clearance allowed Arsenal winger Nicholas Pepe to open the scoring in another disappointing loss.

After such an error-strewn few games, it came to light that de Gea has made more mistakes leading to goals (6) than any other player in the Premier League since the start of last season – an unsettling statistic for United supporters, and those that still regard the Spain international one of the world’s best.

How many more blunders can United’s number one afford before his mistakes are no longer described as ‘uncharacteristic’?

Defendants of the club legend may point to United’s shaky backline as a mitigating circumstance, but it must be considered that goalkeepers playing at bottom-half clubs such as Ben Foster (3) and Lukasz Fabianski (1) have made far fewer mistakes leading to goals.

In truth, the only real way anyone can defend de Gea is by highlighting the number of times he has saved United – with the Red Devils so often on the back foot in recent years, they have heavily relied on de Gea making pheromonal saves to stay in games.

His form before the start of last season was so scintillating that in the long run, United are probably still indebted to him.

But should de Gea continue to descend back into the shaky goalkeeper that joined United nearly nine years ago, there are capable replacements already at the club.

In the immediate future, understudy Sergio Romero could take his place between the sticks – the Argentine made a series of terrific saves during the 0-0 draw with Wolves in the FA Cup and perhaps deserves a chance as the first-choice goalkeeper after being such a loyal deputy to de Gea over the past few years.

While Romero would be a short-term fix, youngster Dean Henderson who is currently on loan at Sheffield United would provide a long-term solution.

Henderson has been fantastic for the South-Yorkshire side over the past year and a half, and would certainly relish the opportunity to step into de Gea’s shoes come the end of the season.

United fans will hope though that manager Ole Gunnar Solskjaer will not be forced to make such a difficult decision, and that de Gea will rediscover his past form and once again establish himself as one of the world’s best.

The Old Trafford club have been devoid of world-class talent in recent years, and de Gea has been one of a minority at United that truly deserve that title.

If errors continue to litter de Gea’s game though, United have to be consigned to losing another elite-level player – whether he remains at the club or not.