It’s three years since former Manchester United defender Jonny Evans tipped Luke Shaw to become the best left-back in the world."Looking at our new defenders, Marcos Rojo and Luke Shaw, I've been really impressed,” Evans said, per ESPN."I had the chance to work with Luke in pre-season and there is no doubt he is going to be the best left-back in the world."Shaw had just become the most expensive teenager in the world after joining the Red Devils from Southampton in a £30 million deal.Fast forward to 2017 and Shaw, now 22, cannot even get a game for the club.The England international has made just one appearance this season, returning from a foot injury in last month’s Carabao Cup win over Burton Albion, and it’s not hard to see why he hasn’t played since.Shaw was taken off after 45 minutes and was later criticised for failing to show a desire to make a real impact by Sky Sports pundit Phil Neville.Mourinho has instead picked Daley Blind and Ashley Young at left-back, proof of just how far Shaw has fallen.

Ferdinand explains Shaw's absence

Yet United hero Rio Ferdinand doesn’t believe that it’s through his form that Shaw isn’t playing.

Instead, Ferdinand believes Mourinho is challenging the player to fight for his place in the first-team.

“It looks like he is testing them mentally,” the 38-year-old told BT Sport, per the Independent.

“Hit them with something – are you going to stay down or are you going to get up and fight? If you get up then he says yes, that's the type of man I want in my team.

“As players, that's what you want in your team. You don't want players who will get one hit and shy away from things.

“One bad pass in a game, shy away from taking the ball again for the next 10 or 15 minutes... that's not how you win titles.

“You need players who are going to be brave receiving the ball, not just physically but mentally, and saying whatever happens here going forward, I will be with you guys shoulder to shoulder.”

Shaw promised more

Shaw posted a throwback photo on Twitter recently in which he remembered his debut for the Red Devils.

“Time flies but there is much more to come!,” he wrote.

Man United fans can only hope that he’s telling the truth.

Does Luke Shaw need to leave Man United to rediscover his best form? Let us know in the comments section below!