Or should that be even more uncomfortable?
Should Manchester United win the race to sign the England international this summer – as leading figures at Borussia Dortmund now believe – City will have an up close and personal reminder of the supreme talent they let go.
Sancho has the potential to be for Guardiola what Kevin De Bruyne and Mo Salah are to Jose Mourinho: an embarrassment.
As with Mourinho’s decision to jettison De Bruyne and Salah during his second spell at Chelsea, there is mitigation regarding Sancho’s case.
City thought they’d struck a deal with one of the gems of their academy – offering him a club record £30,000-a-week before he had even made his first-team debut.
Guardiola and director of football Txiki Begiristain were determined to keep hold of a trio of prospects, including Phil Foden and Brahim Diaz, who they were convinced would be the future of the club.
Chairman Khaldoon al Mubarak had even intervened – assuring the player his route to the first team would not be blocked by Guardiola’s unprecedented spending spree at the Etihad.
“If the end result is to get Sancho to be a starter at Manchester City, there is a balance that needs to be struck,” he said. “There will be different paths, but the end result is how are we going to get these young men to be part of our first team.”
That’s where it gets tricky.
Sancho was convinced he was ready to break into Guardiola’s team. Guardiola, meanwhile, was collecting forwards like they were going out of fashion.
Inside little over a year at City, had had signed Nolito, Leroy Sane, Gabriel Jesus and Bernardo Silva.
He has inherited Sergio Aguero, Raheem Sterling and De Bruyne and, in the very summer he was telling Sancho to commit his future to the Etihad, was desperately trying to complete a deal for Alexis Sanchez.
He would later claim Sancho “didn't want to take this challenge”, but the 20-year-old could hardly be accused of taking the easy way out.
Begiristain is said to have ‘scolded’ him when he turned his back on a new contract. Guardiola promptly dropped him from the club’s pre-season tour to the US – and Sancho then refused to turn up to training.
It was an unseemly end to his time at City, but as inevitable as De Bruyne’s decision to turn his back on Chelsea when Mourinho refused to play him ahead of Eden Hazard, a peak Juan Mata, Cesc Fabregas or Oscar at the time the Belgian was desperate to make his breakthrough.
That Guardiola has gone on to oversee a period of unprecedented dominance in City’s history has understandably shielded him from criticism of his handling of Sancho. But instead of creating a pathway for one of the most exciting prospects in world football, he placed ever more expensively accrued obstacles in his way.
Comparisons can be drawn with Sir Alex Ferguson and the Class of 92.
Paul Ince, Mark Hughes and Andrei Kanchelskis needed to be moved on to integrate Nicky Butt, David Beckham and Paul Scholes. Later – and in slightly different circumstances – Ruud van Nistelrooy made way to allow Cristiano Ronaldo to flourish.
Guardiola is convinced City could have done no more to keep Sancho.
“We tried absolutely everything to help them to play with us and he wanted to play in the first team,” he said after Sancho signed for Dortmund in a deal worth around £10m in 2017. “There were many teams interested in him because he is a huge player, a huge talent. That is why we offered him the best contract possible to continue with us, but he decided to move on and with that we cannot fight.
“I cannot assure even the best players we have like Sergio and other ones, that you are going to play. I am not going to tell you ‘I assure you, you will play all the games in the season’ to sign the contract. I would be a liar, it’s not true.”
Dortmund were prepared to offer the assurances Sancho was seeking, and doubled down on their faith in him by handing him the No7 shirt vacated by Barcelona-bound Ousmane Dembele.
It was a symbolic gesture, underlining the German club’s strategy of buying the best emerging talent before selling for a huge profit. Dembele had only spent a year at Dortmund after signing from Rennes for around £14m. He was sold to Barca for £135.5m.
Dortmund stand to make a similar profit on Sancho, with United prepared to make him the most expensive player in their history. Chelsea are interested, too, and undeterred by a fee that could reach £120m.
City have the option to match any bid – but it’s highly unlikely they would be willing to smash their own record on player they already let slip through their grasp.
At Old Trafford, the No7 shirt is ready and waiting to be filled. Ole Gunnar Solskjaer and Ed Woodward believe Sancho is a player in-keeping with the club’s finest attacking traditions.
They believe he can become a United icon and are ready to give him what he so desired at City – the chance to take centre stage.
Should he do that, should he prove to be a catalyst to United’s resurgence after seven years in City’s shadow, then may just be the awkward question that dogs Guardiola long after he has left these shores.