Still going well in the Premier League, it was an unwanted inconvenience for Manchester United to suffer a surprise defeat to Middlesbrough in the Capital One Cup on penalties yesterday evening.

In an eventual loss described as lucky on Boro's part by Red Devils boss Louis van Gaal, today's headlines have centred upon the FA looking into the matter of a laser being shone in Wayne Rooney's eyes by a Middlesbrough supporter prior to him having his spot kick saved by Tomas Mejias in the shoot-out.

In truth, the game was quite exciting for the neutral with Boro punching above their weight in giving as good as they got against a United side that also had their chances with Jesse Lingard agonisingly finding the woodwork for the second time in two successive games.

But it was Aitor Karanka's side that progressed to the quarter-finals in the end and on the face of it, it is something of a shame for van Gaal who probably would've earmarked the competition as one of the easier to win with the Dutchman still waiting for his first silverware in charge at Old Trafford.

With Arsenal and Chelsea exiting the night before as well, both United's great rivals Liverpool and Manchester City will now harbour more realistic ambitions of scooping the prize.

An underrated competition for some if not a majority, we're talking about underrated in different terms today and specially those United players of yesteryear that perhaps didn't receive all the glowing credit they maybe merited.

Here's who our punters believe are the five most underrated Manchester United players of all-time.

[ffc-gallery]

Click on the image below to reveal the five most underrated Manchester United players of all-time.

Old Trafford

[/ffc-gallery]

Denis Irwin

Irwin

Whenever you hear 20-something Manchester United fans marvel about their defence of yesteryear, naturally the names Nemanja Vidic and Rio Ferdinand will be joined by the likes of Gary Neville, Ronny Johnsen and so on, some forget the consistent heroics of Irishman Denis Irwin.

Spending over a decade at Old Trafford between 1990 and 2002, Irwin made a mighty 511 starts for the Red Devils, scoring 33 times to boot which isn't bad for a defender.

Somebody who was completely and utterly professional under the guidance of Sir Alex Ferguson, Irwin was Mr consistent and somebody that deserves all the plaudits for his consistency.

After all, he won 19 major honours in a star-studded spell at United!

Park Ji-Sung

Park

It was only nearer the end of his spell at Old Trafford that Manchester United fans started giving regular accolades to Park Ji-Sung who proved to be an absolute bargain for the Red Devils at just £4 million from PSV Eindhoven back in 2005.

For that basement price, what United fans received were 134 Premier League appearances from the South Korean midfielder where he showcased he was a jack of all trades-type midfielder, capable of not only sticking his boot in but supplementing attacks and scoring as well.

Arsenal fans will tell you that Park always seemed to save his best performances for games against the Gunners and it's true because Sir Alex Ferguson always tended to throw the tireless Ji-Sung into crunch top four battles simply because his energy would end up countering the opposition.

Unfortunately for Park, following his trophy-laden spell at Old Trafford, the less said about his then move to Queens Park Rangers, the better!

Brian McClair

McClair

For early 20-something Manchester United supporters, they may only remember Brian McClair as that guy who was last on the Red Devils' page in the nineties' Premier League sticker books but after hanging around probably longer than he should've on a regular playing level, we mustn't forget he was a lethal finisher earlier in his United career.

Having been on United's books for an elongated spell between 1987 and 1998, McClair departed Old Trafford with a goalscoring record of 88 strikes in 355 appearances which was no mean feat at all for the Scotsman.

Scoring 24 times in his debut season for the Red Devils, perhaps McClair was underrated by a later generation of United fans who didn't see him burst onto the scene so fantastically.

Sticking around wasn't so bad either because in total, McClair lifted 15 major honours in his time at the club.

Darren Fletcher

Football - Manchester United v Sunderland - Capital One Cup Semi Final Second Leg - Old Trafford - 22/1/14
Craig Gardner of Sunderland in action with Manchester United's Darren Fletcher
Mandatory Credit: Action Images / Lee Smith
Livepic
EDITORIAL USE ONLY. No use with unauthorized audio, video, data, fixture lists, club/league logos or ìliveî services. Online in-match use limited to 45 images, no video emulation. No use in betting, games or single club/league/player publications.  Please co

Having only broken his Manchester United association last January where he signed for West Bromwich Albion, there's no doubting that Darren Fletcher was an incredible servant to the Red Devils across a 12-year spell.

Somebody who was never a world class talent, yet somebody who was always doing the dirty work around other world class players, Fletcher never let himself down in the United side and never believed he was worse than other players.

Having unfortunately experienced health-related issues later in his United career, everybody was delighted to see Fletcher return to action more recently and now the captain at West Bromwich Albion, there's no doubting that all his experience gained in his career is helping the younger players around him at The Hawthorns.

Jaap Stam

Stam

Everybody will immediately remember the rather bitter end to Jaap Stam's Manchester United career when the Dutchman released an autobiography that infamously riled Sir Alex Ferguson who then sold him to Lazio.

But prior to this, Stam did little wrong in his United career and was part of a Red Devils team that scooped three Premier League titles among other honours during his time at Old Trafford.

An incredibly tough customer, Stam was a rugged performer who intimidated opposition strikers and thankfully for United fans, the club have been able to emulate the performances of Stam in the transfer market via the signing of Nemanja Vidic later in 2006 who can definitely pay claim to being a true Manchester United legend.

With much of the praise going to the likes of Dwight Yorke, Andy Cole and Ryan Giggs during these boom United years, the likes of Stam helped lay down solid foundations for these forward players to thrive ahead of him.