Manchester United face the threat of a return to the days of ‘Green and Gold’ protests as impatient supporters grow increasingly angry at what they see as a lack of investment in the squad by owners the Glazer family.

With just over 10 days left in the transfer window, Louis van Gaal’s squad remains dreadfully short of the quality it needs if the Dutch manager is to steer the club back towards the top of the Barclays Premier League.

Executive vice-chairman Ed Woodward still hopes to conclude a deal for Sporting Lisbon central defender Marcos Rojo, while United hope that Angel di Maria can be tempted from Real Madrid despite the fact they cannot offer him European football. They are also talking to Ajax about Holland utility man Daley Blind.

VIDEO Scroll down to watch Manchester United target Di Maria in a spat with Ronaldo

Bad result: Manchester United lost their opening game of the weekend against Swansea City on Saturday

Unhappy fans: Sections of the Old Trafford faithful could protest against the Glazer family against QPR

Protest: Manchester United fans remain far from happy with the club's owners the Glazer family

Displeased: Louis van Gaal knows he needs to add to his squad before the transfer window slams shut

The club’s fans, though, are furious that the most important season in recent times has begun with United thrashing around for new players when they were led to believe all key business would be concluded shortly after the World Cup finished at the start of July.

Now a growing group of supporters will see what happens over the next week or so before planning a possible protest at Old Trafford when United face QPR on September 14.

That would be the first game after the transfer window closes, with some fans talking about a return to the ‘Green and Gold’ campaign that was a feature of anti-Glazer feeling back in 2010.

Dissent has grown rapidly in the wake of Saturday’s dismal home defeat by Swansea and social media has been awash with #GlazerOut messages over the weekend.

Sean Bones, of the Manchester United Supporters’ Trust, said: ‘United supporters worldwide have hit out in huge numbers against the Glazer family’s ownership of Manchester United via Twitter and Facebook.

‘It’s obviously something that will be a huge concern to the current sponsors who have invested a lot of money in Manchester United as a brand.

‘There will be a lot of attention to see how the New York Stock Exchange views the negative reaction by supporters in terms of the Glazers’ handling of United.’

While some United supporters blame Woodward for United’s failure to land players this summer, others blame Van Gaal’s predecessor David Moyes, who led the team to seventh last season after inheriting a team of title winners from Sir Alex Ferguson.

Transfer target: Sporting Lisbon defender Marcos Rojo is closing in on a move to Manchester United

Blame game: Manchester United's executive vice-chairman has failed to land top targets this summer

Beneath all that, however, lies ongoing resentment towards the Glazer family; vast numbers of United fans firmly believe the current problems are the result of years of under-investment by the Americans.

It was sobering for followers of the club with the largest turnover in British football to see a Premier League opening weekend featuring a host of big-name, expensive players who have signed for other clubs over the summer.

United have signed two expensive players — midfielder Ander Herrera and Luke Shaw — for more than £50m but Woodward is now facing the tricky obstacle of a lack of Champions League football as he tries to lure the really big stars to Manchester.

Woodward has said he is confident that the history, size and tradition of United will prove enough when it comes to attracting new players.

However, the case of Di Maria throws that into doubt. The Argentina winger knows Real need to raise money through sales and also that he may not command a first-team place at the Bernabeu this season.

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Summer signings: Manchester United have brought in Ander Herrera and Luke Shaw so far this summer

Wanted man: Manchester United are keen on bringing Real Madrid's Angel di Maria to Old Trafford

Di Maria has told friends that United’s weekly wage offer is the highest he has received from any club, yet he is unsure about whether to join a club that has no place in the only European competition that really matters to the truly stellar names these days.

Inside the corridors of power at Old Trafford, there is no panic yet as the club still has more than 10 days to bring in players. Van Gaal has tried to remain phlegmatic in public, saying that it ‘only takes 24 hours’ to sign a player.

However, it is understood the United boss is already irritable and anxious about the matter and fears he may end up signing players beneath the required quality simply because he needs numbers in his squad.

Saturday’s game saw him start without nine players who are injured and he has subsequently lost young midfielder Jesse Lingard to a lower leg injury that saw him leave hospital on crutches.