For our Manchester United supporters here in the Football Transfer Tavern, everything was going rather swimmingly for the Red Devils up until their thumping 3-0 loss at Arsenal on Sunday afternoon.

Having sat on top of the Premier League for the first time since Sir Alex Ferguson's tenure, United have now swiftly been displaced by cross-town rivals Manchester City with the Gunners themselves leapfrogging them into second to boot.

Immediately taken by surprise given Arsenal's fast start at Emirates Stadium on the weekend, United were unable to recover with van Gaal claiming that his side lacked the will to win in a rather damning assessment.

Prior to this off day, United have been making a good fist of a title challenge this term with nobody really expecting them to be at the forefront of the race this season but in Anthony Martial, the French youngster has given the Red Devils that added lift up top.

Boasting more squad depth having added the likes of Morgan Schneiderlin and Bastian Schweinsteiger this season, United should boast more quality and experience in their title challenge this term but their critics still think they're rather light up top and at the back.

While United fans unfortunately have to stew on their Arsenal defeat during the international break, we're taking this moment to take a look at five of the worst Manchester United debuts of all-time.

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Click on the image below to reveal the five worst Manchester United debuts of all-time.

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Eric Djemba-Djemba

Djemba-Djemba

So bad they named him twice, everybody knows Eric Djemba-Djemba turned out to be one of Sir Alex Ferguson's biggest ever flops but can you remember his Manchester United debut now?

It came back in the 2003 FA Community Shield against Arsenal where despite the Red Devils claiming an eventual victory over the Gunners on penalties, the Cameroonian midfielder committed a tackle described as "obscene" by Arsene Wenger on Sol Campbell.

In what was always a spiky affair during the Fergie versus Wenger years, Francis Jeffers saw red for kicking out at Phil Neville while Djemba-Djemba's deliberate looking follow through on Campbell which provoked a kick out from the former England international also set the tone.

With both Campbell and Djemba-Djemba avoiding a red card, you couldn't help but feel the United player never ever learnt that his over-physical approach was simply a burden in the eyes of United supporters and ultimately, he was nowhere near good enough to replace the boots left by an ageing Roy Keane.

David De Gea

De Gea

It's harder to remember nowadays that David De Gea endured a torrid time of it at the start of his Manchester United career where he'd often be criticised for flapping at the ball in unconvincing performances.

Now arguably the best goalkeeper in world football, it is a credit to the Spanish international how he's turned opinions around in his time at Old Trafford but it wasn't always this way.

Making his Premier League debut against West Bromwich Albion away on the opening day in August 2011, despite the Red Devils running out 2-1 victors on the day at The Hawthorns, De Gea received heavy criticism for failing to prevent a Shane Long equaliser on 37 minutes.

With Sir Alex Ferguson having conceded that De Gea was in a "learning process" after the game, United fans were naturally expectant having shelled out a British record fee for a goalkeeper of £17.8 million for his services.

Fast forward to 2015 and he's been worth every penny for the Red Devils.

Dong Fangzhuo

Dong

In a case of this game away at Chelsea's home of Stamford Bridge being his first and last Premier League appearance in a Manchester United shirt back in May 2007, Dong Fangzhuo did little to avenge the stereotype that he was simply brought into the club to shift shirts over in the Far East.

Eyebrows were raised when the former Chinese international was signed by Sir Alex Ferguson back in 2004 given his lack of experience and eligibility with the player having to bide his time for his United debut in being sent out on loan to Royal Antwerp.

In truth, Dong was rather fearsome in his time on loan in Belgium striking an incredible 34 goals in 71 appearances over two seasons but when he eventually made his English top flight debut in 2007, you could see he just wasn't cut out for the very highest level.

In fairness, his debut game against Chelsea which ended 0-0 came after United had already landed the title but the Chinese striker didn't show anything to suggest he was worth keeping on and it seemed Sir Alex Ferguson agreed with this being the player's solitary performance in the top flight.

Kleberson

Kleberson

Like Djemba-Djemba mentioned before, Kleberson will forever go down as one of the all-time United flops but to be honest, it was never going to be any other way after a forgettable debut against Wolverhampton Wanderers that was described as "inauspicious" by a Wolves fan site back in August 2003.

The midfielder was signed on the back of an impressive showing at the 2002 World Cup in Korea and Japan where Kleberson impressed alongside Gilberto Silva who went on to sign for Arsenal but positive stories regarding Kleberson started and ended there.

To be fair to the player, he did succumb to a long-term injury in his second performance for the club after the Wolves game and never really recovered having only gone on to make a total of 20 appearances for the Red Devils.

It just wasn't to be for the Brazilian!

Victor Valdes

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Manchester United's Victor Valdes
Action Images via Reuters / Craig Brough
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Currently out in the wilderness at Old Trafford with Louis van Gaal having banished him to the reserves, Victor Valdes is enduring a low point in his largely illustrious career right now.

In fairness, his United career never really got going with the Spanish international only having made two Premier League appearances so far in the final game of last season away to Hull City and before that to Arsenal in his competitive debut.

After an injury to David De Gea in the second-half of that game, United fans and Valdes himself were taken by surprise when he was immediately pressed into action for the latter stages after a 14-month absence from the game,

Picking the ball out of his own net just eight minutes into his United debut after Tyler Blackett deflected a Theo Walcott shot into the United goal, the Gunners equalised on United's 1-0 scoreline giving Arsene Wenger's men the advantage as they went on to finish third in the Premier League and in that important automatic qualification spot for the Champions League.