Conceding three goals in any Premier League match is almost unheard of for Manchester United, which is why Sunday's 3-2 loss at Brighton and Hove Albion was so concerning for Jose Mourinho.
Luckily for United, Tottenham are coming to town and they have lost on each of their last four visits to Old Trafford without scoring a single goal, a record Mauricio Pochettino will be desperate to improve.
Talk of United being in crisis is surely too early two games into the season but Mourinho's pre-season warning a "difficult" campaign was in store appears to be becoming a self-fulfilling prophecy.
That Spurs will travel north with Toby Alderweireld - reportedly a top target for Mourinho during the transfer window - will only highlight United's poor defensive recruitment even further.
Ahead of Monday's meeting at Old Trafford, we assess the strengths and weaknesses of Manchester United and Tottenham's defences.
MANCHESTER UNITED
Prior to losing at Brighton, United had not shipped three or more on the road in the Premier League since October 2016, a 4-0 thumping at the hands of Mourinho's old club Chelsea, demonstrating the extent of their defensive issues.
Mourinho made it clear he wanted to sign a centre-back during the transfer window, with England's World Cup hero Harry Maguire among those linked, along with Alderweireld and Bayern Munich defender Jerome Boateng.
But it was notable at Brighton how it was two Mourinho signings, Victor Lindelof and Eric Bailly, who were all at sea as wily campaigner Glenn Murray, 34, caused all kinds of issues for the United defence.
While often a laughing stock on social media for his funny faces and desperate attempted clearances, Opta data indicates Phil Jones is actually the most effective of the centre-backs available to Mourinho.
Jones, once tipped by Alex Ferguson to become the greatest player in United's glorious history, has contributed to 15 clean sheets since the start of the 2017-18 Premier League season, even though he only played in 23 games.
The England international made over six recoveries a game on average during that period, while conceding just 0.5 fouls per game, on top of a highly impressive passing accuracy rate of 91.2 per cent.
While Mourinho was demanding an expensive answer to United's defensive deficiencies, might one of the solutions to their problems at the back be right under his nose?
Bailly looks like he has the potential to develop into a world-class defender but the jury is certainly out on Lindelof, who has struggled to adapt to the Premier League since joining from Benfica in June 2017.
TOTTENHAM
Mauricio Pochettino reintegrating Alderweireld into Tottenham's team is the good news story the club's fans have been waiting for.
A bad couple of weeks off the pitch included delays with the rebuilding of White Hart Lane, which followed a transfer window without a single new arrival - Spurs the only Premier League team that did not strengthen - while club captain Hugo Lloris was charged with drink-driving on Friday.
Alderweireld could prove the cliched 'like a new signing' for Spurs, who head to Manchester with maximum points after recording wins against Newcastle United and Fulham in their first two matches of the new campaign.
But the Belgium centre-back is in the last year of his contract and showed little form in an injury-affected 2017-18 to suggest he should be considered among Europe's elite defenders.
Alderweireld has featured in just five clean sheets in his 15 Premier League appearances since the start of last term, recording only five blocks and four interceptions in those matches.
Belgium colleague Jan Vertonghen, meanwhile, completed 1.9 tackles per game on average in that spell, while the 31-year-old also made 6.8 recoveries per match - more than any other United or Spurs defender.
Pochettino addressed the issue of how to fit Alderweireld, Vertonghen and rising star Davinson Sanchez into his team by fielding a back three against Fulham, while versatile England international Eric Dier is a further option at the back.
Sanchez is raw but extremely promising, with Dier and Vertonghen both extremely reliable - Mourinho would love to have such strength in defensive depth as he assesses his options for containing the World Cup's Golden Boot winner Harry Kane.
