Manchester United's summer transfer window had so much potential.

The Red Devils entered the market with designs on players like Gareth Bale and swiftly secured the signing of Fred from Shakhtar Donetsk, but the club soon stagnated afterwards.

There was no shortage of names being considered by Jose Mourinho yet very few deals came to fruition and the Portuguese manager was left deflated heading into Deadline Day.

"The market closes today. It is time for me to stop thinking about the market," he lamented on Thursday morning.

"I am not confident. I have to focus on the players I have and the next few matches."

Frustrating summer for Man Utd

Mourinho had been chasing a new centre-back in particular with Toby Alderweireld, Diego Godin, Yerry Mina and Jerome Boateng emerging as the main contenders this week.

In the end, though, Mourinho was left to settle with his current squad and the same can be said for his designs for the United midfield.

Although Fred was introduced to replace the retiring Michael Carrick, numerous reports suggested Mourinho wanted another top-level player to pull the strings at Old Trafford.

Agent reveals Mourinho transfer secrets

And now the transfer window has slammed shut, the comments of football agent Paul Stefani - who works with Axel Witsel - show United had some pretty major plans for their midfield this summer.

It leaves fans wondering: what could have been?

Speaking to Belgian outlet HLN, and via Sky Sports, Stefani explained: "Manchester United wanted Axel Witsel, Napoli too. But I told Axel: 'At Dortmund you are the number one, at Manchester you are one of the many... and at Napoli too.'

"I know from a very good source that Mourinho said he wanted Witsel, but not in the first place.

"N'Golo Kante topped his list.

"Eventually Axel said: 'Do me a favour and finish it as quickly as possible because I really want to go to Dortmund'."

That's right, United's number one target was none other than Kante.

You certainly can't fault Mourinho for ambition and considering neither him nor Witsel had been linked in the English media, it proves quite the bombshell for United fans.

Supporters would certainly be talking differently about their chances next season if they had Kante lining up alongside Nemanja Matic and Fred.

Nevertheless, it seems Chelsea held off their rivals just as they did with Willian who was believed to be another target of Mourinho's.

The situation leaves United with plenty to do ahead of the new season and an increasingly slim chance of going all the way in 2018/19.

And anything short of winning the trophy will leave fingers pointing at their chaotic summer transfer window that, ultimately, promised so much.

Where do you think United will finish this season? Have your say in the comments section below.