Manchester United slumped to their worst defeat in nine years on Sunday as Tottenham's 6-1 rout at Old Trafford plunged the Red Devils back into a familiar state of crisis.

United have not contended for the Premier League title since legendary former manager Alex Ferguson retired in 2013.

However, hopes were high that the club were on the up as they secured a return to the Champions League on the back of a 14-game unbeaten run to finish the Premier League last season.

That optimism has proven misguided inside the first month of the new campaign as United were also soundly beaten 3-1 at home to Crystal Palace and were incredibly fortunate to escape with a 3-2 victory at Brighton last weekend.

AFP Sport looks at three major reasons behind United's woes.

Years of Glazer ownership

United's owners and decision-makers have been fiercely criticised for failing to strengthen as their rivals have splashed out in the transfer market despite the economic cloud caused by coronavirus.

However, United's finances have been hamstrung by the Glazer family's leveraged buy out of the club in 2005.

Unlike most of their Premier League rivals who can count on net investment from their ownership, over £1 billion has flowed out of United over the past 15 years in dividends.

Thanks to huge revenues on the back of the club's success during Ferguson's 27 years in charge, United have still spent heavily in the transfer market and on wages since the Scot's departure.

But with executive vice-chairman Ed Woodward the man doing the deals and no sporting director, United lack the structure behind the scenes to get the best return on their investment.

While a defence that has conceded 11 goals in their opening three league games badly needs strengthening, United have instead spent most of the summer in a forlorn pursuit of Borussia Dortmund winger Jadon Sancho and seem set to bring in Uruguayan striker Edison Cavani on a free transfer.

Tottenham boss Jose Mourinho, who was sacked by United in December 2018, rubbed salt into his old club's wounds by praising Spurs' structure "that made it possible to have this squad" after significantly bolstering his options in recent weeks.

Spotlight on Solskjaer

The ire of most fans may be on his superiors, but there are doubts United can ever rediscover their former glories with Ole Gunnar Solskjaer as manager.

Solskjaer was initially seen as a spot-gap until the end of the 2018/19 season after Mourinho's sacking before a blistering run of form earned him a three-year deal.

Progress was made last season to finish third last season, but United were still 33 points adrift of champions Liverpool.

If results do not improve, the roles could be reversed with United swooping for a former Tottenham manager.

Mauricio Pochettino remains without a club since he was sacked by Spurs a year ago just months after leading them to a first ever Champions League final.

Dodgy defence

United's defensive record could be even worse had Brighton not hit the woodwork five times in defeat last weekend.

Harry Maguire may be the world's most expensive defender, but he does not look it after an close season dogged by off-field troubles.

Solskjaer dropped Victor Lindelof in favour of Eric Bailly on Sunday, but the Ivorian was one of the biggest culprits for the defeat and was lucky to stay on the field for a couple of petulant kicks on Harry Kane.

The failure to find the right partner for Maguire threatens to derail their season, while former United defender Patrice Evra questioned why the Maguire's place is also not up for grabs.

Left-back is the one defensive position that may be upgraded on deadline day with a deal with Porto for Alex Telles reportedly close.