Much like any club, Sunderland have endured their fair share of transfer heartache, making costly mistakes in the window by missing out on high-profile stars who have gone on to blossom elsewhere.
The most notable example that left supporters pulling their hair out in recent times was their failure to sign Virgil van Dijk in 2015 for just £8m.
At the time, the centre-back was plying his trade at Celtic and although Gus Poyet later recalled being "very very interested" in the Dutchman on the What the Falk podcast, he slipped through their grasp and instead joined Southampton six months later.
The rest, as they say, is history, with Van Dijk joining Liverpool for £75m in 2017 and becoming one of the greatest defenders of all time.
While missing out on the towering titan is something they'll live to regret for eternity, he isn't the only former Sunderland target to have ripped it up in the Premier League, ruing their failure to snap up treble-winning magician, Kevin De Bruyne.
Did Sunderland almost sign Kevin de Bruyne?
Back in the summer of 2011, the Black Cats had just recorded a top-half finish in the Premier League and Steve Bruce was attempting to assemble a squad that could challenge in the upper echelons of the table.
Acquiring the likes of Conor Wickham, Ahmed Elmohamady and Craig Gardner, the Englishman would have blown them out of the water, and some, if he had managed to capture De Bruyne.
It was reported that Sunderland was one of several clubs lining up a move to sign the 19-year-old Genk attacking midfielder.
Aston Villa were also said to be vying for his signature, but he ended up penning a deal to sign for Chelsea six months later, in January 2012.
While they wouldn't have known it at the time, De Bruyne would go on to become one of the greatest midfielders to grace the beautiful game, ultimately failing at Chelsea, making a name for himself at Wolfsburg before reaching the pinnacle of his powers as a world-class technician at Manchester City.
What has De Bruyne achieved since?
To have shown a keen interest in an all-time Premier League great when he was available for just £6m will likely sting as far as Sunderland are concerned, having watched him enjoy a glittering career in Manchester.
Winning countless personal accolades, including the PFA Player of the Year award in the 2019/20 and 2020/21 campaigns, the magician has reached an untouchable legacy at Man City through his wand of a right foot and his ability to conjure up moments of sheer brilliance.
Lauded by Pep Guardiola as "one of the greatest players of all time", the Belgian has become a killer pass specialist, excelling with his vision, almost unstoppable whipped crosses and sublime lofted through balls from deep.
As far as creative midfielders go, De Bruyne has everything in his locker and is the main contributor to Erling Haaland's insane goal-scoring numbers, assisting the Norwegian an impressive eight times last term.
For many years, the brilliant Belgian has orchestrated their dominance at the top through his impeccable ball-playing abilities, scoring 96 and chalking up an impressive 153 assists in 385 appearances for City.
With their dominance reaching new heights last season as Guardiola's side wrote their names into the history books by winning a historic treble, the assist machine was only praised further for the role he played in their path to success having recorded an eye-watering 25-goal contributions in 32 Premier League matches, 18 of which were assists.
Dubbed by Gary Neville as "the best player in the league", De Bruyne's influence is accentuated further when he's not in the side and since being sidelined with an injury, City have desperately the ease at which he unlocks opposition defences, penetrating low blocks with his relentless crossing ability.
The midfield magician, who is now valued at £31.5m as per Football Transfers, is reaching the twilight of his career and while his powers as a master creator will wane in the coming years, Sunderland will look back at what could have been for eternity.