Brad Friedel
Favouring Sander Westerveld as their number one Liverpool allowed the then-follically-blessed American to slip through their gloves in 2000 to join a Blackburn side intent on promotion. A return to the Premier League swiftly secured Friedel went on to make 287 steadfast appearances for Rovers including a Man of the Match display in the Worthington Cup Final and even finding himself on the score-sheet in a league game at Charlton.
One particularly outstanding display prompted opposition gaffer Gordon Strachan to believe big Brad got changed in a phone box prior to the game with a big S hidden beneath his jersey. Fourteen years on and Liverpool presumably still regret their decision. Would Friedel have dived the wrong way for Rooney's opener at Old Trafford on Sunday?
Sol Campbell
By some considerable distance the most controversial British Bosman of them all, Campbell went from hero to Judas with a stroke of a pen in 2001 when he switched from Spurs to Arsenal citing hunger for silverware as his motivation.
To that end Sol's decision was perhaps warranted snagging two league titles and a trio of FA Cup triumphs, not to mention being part of the famed 'Invincibles' team of 2003/04. The 'betrayal' though still runs deep for half of north London and an apology - of sorts - this year was as well-received as a nightmare ex texting 'Still miss you babe' on your wedding day.
Esteban Cambiasso
Any club would miss Claude Makelele as the heartbeat of their XI and in 2003 Real Madrid were no exception, trying out a succession of players in their attempt to replace the irreplaceable. One such candidate was Cambiasso who they had plucked several years earlier from Argentina as a raw teen. A game here, a game there, the player nicknamed - even in his early 20s - as 'Old Man' was never afforded a chance to shine and in 2004 Real allowed his contract to run down and move to Inter.
In Serie A the midfield schemer soon became legend, racking up more club honours than any Argentinean since Di Stefano including five successive league titles and a Champions League crown. One of the finest players to grace the San Siro in modern times, his decade of exceptional service makes Real's decision a galactic howler.
Jay Jay Okocha
Working within a tight budget at Bolton, the new freedom of movement ruling proved a godsend for Sam Allardyce who wasted no time in luring some big names to the Reebok. Youri Djorkaeff and Fernando Hierro blew the flat-cap image of the club clean off while Kevin Davies provided 10 years of argy-bargy for nowt but his wages.
By far the most impressive coup though was tempting Jay Jay Okocha over from Paris. The Nigerian who was so good they named him twice brought magic in abundance to Bolton in 124 appearances that included jaw-dropping flicks, tricks and free-kicks. Now Wanderers fans watch Darren Pratley misplace a five yard pass and quietly weep into their pie.
Gary McAllister
Described by Gerard Houllier as his 'most inspirational signing', the 35-year-old's switch from Coventry to Anfield raised an eyebrow or two back in 2000. The Scot had enjoyed a successful career picking our artful passes but surely his best days were behind him and would prove to be nothing more than squad fodder?
He was anything but. McAllister revelled in two Indian summers of excellence patrolling the Anfield turf while adding five medals to his cabinet that included a treble. Even to neutrals it was a joy to see this likable aging maestro roll back the years.