Tottenham's defensive display at Everton has left many fans very worried ahead of Saturday evening's Premier League clash away at Man City.
Keeping a clean sheet last Sunday in the win over West Brom, Spurs then conceded five at Goodison Park as they crashed out of the FA Cup in a 5-4 thriller.
Given that area of the pitch has been a major issue for Jose Mourinho since the season started as he has constantly shuffled things about to try and find his best combination, you can understand why some feel rather nervous with Man City in top form.
Defeating Pep Guardiola's team 2-0 at Tottenham Hotspur Stadium in November, City have come from nowhere since just prior to Christmas to open up a five-point gap at the top of the Premier League table.
Following the disappointing 1-1 draw at home to West Brom, they have won ten league games on the bounce and now look more like the side that ripped teams to shreds when they won back-to-back titles in 2018 and 2019.
Now the outright favourites to retain the top prize from Liverpool, what is worrying for their rivals is that Sergio Aguero has been missing for the vast majority of the season and influential midfielder Kevin De Bruyne has not played since the 2-0 win over Aston Villa last month.
What has also helped City over the past two months is eight clean sheets from a possible ten in the league, with Chelsea and Liverpool the only two teams to score past them in that period.
John Stones has come on in leaps and bounds after his Man City future looked to be over after a couple of tough seasons at the club, while the summer signing of Ruben Dias from Benfica has transformed the side.
Spending millions upon millions in the past in their attempt to put together the perfect backline, Guardiola appears to have struck gold with the arrival of the centre-back for £65million.
Prior to his move to the Etihad, the 23-year-old was heavily linked with Tottenham but his price tag was always going to be a major stumbling block with clubs having limited summer funds due to the coronavirus pandemic.
A client of Mourinho's agent Jorge Mendes, it came as no surprise to see the highly-rated player in the headlines regarding a transfer to north London due to Spurs' excellent relationship with Benfica and the fact they needed a new centre-back to fix a long-standing issue.
With Tottenham and Mourinho big fans of Dias, he was always going to be too expensive to buy even with Benfica crashing out of the Champions League which made a summer sale inevitable.
After missing out on deals for Dias and Inter Milan's Milan Skriniar, Spurs instead planned for the future by bringing in talented youngster Joe Rodon after making a huge impression in the Championship with Swansea City.
Speaking after the Welshman's excellent showing in the win over Sheffield United last month, Mourinho pointed to the fact that he had to bring in a defender with potential to develop rather than splashing big money on one to fix the problems right away.
"He played well. He did many things well, a couple of things not so well, but he's a player who of course was playing in the Championship. A young guy, he has to learn," he said in his post-match press conference.
"One thing is you want a central defender and you pay £70m for one of the top centre-backs in Europe, then you resolve your problems.
"Another thing is to get a good player, but a player who needs to develop. With Joe, that's the situation. He has to learn, he has to make mistakes, he has to play, he has to not play.
"We have to try to give him conditions to perform. but potentially, potentially of course, he's a good player who can become much much better."
Whereas Rodon is quite clearly a player who is going to need time to become a top defender and a Tottenham regular, City have fixed their backline issue instantly with the addition of Dias.
Clearly not needing time to get up to speed with the pace and intensity of the Premier League as some foreign players do, Dias, who isn't your typical Guardiola player as he is a defender first and foremost rather than a ball-playing centre-back, has revolutionised his new team like Virgil van Dijk did at Liverpool following his move from Southampton.
Dias had made a huge impression on many since his move to Man City in September, notably his boss Guardiola.
“When you buy players always you have this quality but you never know what is going to happen," explained the Spaniard last month, as reported by talkSPORT.
“He is a guy that can play every three days. He recovers immediately and his ability is incredible, as is his understanding of the game.
“He wants to learn and all of us were impressed how he takes care of his body and mind, every day. We were surprised a lot.
“The day after [a game] – 8.30 in the morning in the gym. He makes his routine, he eats perfectly. He lives 24 hours for his profession.
“I can assure you that we signed one incredible player for the next five, six, seven years. That is not easy to find.”
Having brought in a player who can play a pivotal role at the back for potentially the next seven years, Mourinho will be hoping he can do likewise in the summer as he looks to fix his problems at the back for good.
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One thing for sure is that Daniel Levy is going to have to pay upwards of the £42m it cost to sign Davinson Sanchez in 2017 if they want the issue to be finally solved.
With the head coach still not knowing his perfect backline and the answer to his defensive conundrum, his counterpart can rest safe in the knowledge that he now has someone who has not only transformed his defence but also the team.
Now set to come up against the Portuguese international for the second time this season, Mourinho and the club's fans may well be looking on and thinking what might have been had the club had the funds to bring Dias to the capital ahead of the season.
Mourinho and Tottenham's loss is certainly Guardiola and Man City's gain.