12 players Arsenal, Man Utd, Chelsea and Liverpool should never have sold
Petr Cech (Chelsea)
We may as well start with the most obvious of all. Allowing Petr Cech to leave Chelsea after more than a decade of faithful service was one thing; to allow him to join Arsenal, a title rival and sworn enemy, was quite another. Cech has (of course) been outstanding for his new team, who are mounting a title challenge as Chelsea wallow towards the foot of the table. A rare example of Roman Abramovich allowing sentiment to cloud his judgement.
Lassana Diarra (Arsenal)
The midfield tough guy that Arsenal have been lacking for so many seasons - at least until the emergence of Francis Coquelin - was right under their noses in 2007. But a lack of regular football meant Lassana Diarra chose to move to Portsmouth, where he won the FA Cup and earned himself a move to Real Madrid. He won the double there in 2012. "If [Diarra] was able to be patient, he would have got his chance," Wenger said. "It turned out he wasn't capable of that. With Euro 2008 in mind, he panicked. I did explain when he joined that he might have to be patient, and he acknowledged it, but he couldn't cope with the situation, and also did not want to go on loan anywhere either."
Nemanja Matic (Chelsea)
Made precious little impact with Chelsea after joining in August 2009 and was a makeweight in the deal that saw David Luiz arrive from Benfica in 2011. It was a costly decision: Chelsea had to pay £21million to re-sign him in Jan 2014, as the club sought the midfield enforcer that could turn them into champions. He was a huge part of Jose Mourinho's all-conquering side last season, although he has faded this term.
Javier Hernandez (Manchester United)
United must regret their decision to off-load Hernandez last summer, given their problems in front of goal this season. The Mexico international was, it is true, an inconsistent player at Old Trafford but he has flourished with new side Bayer Leverkusen, where he has 11 goals in 14 games.
Pepe Reina (Liverpool)
Liverpool's inability to trust in their goalkeepers this season has been one of the side's fatal flaws, and their irritation can only be magnified by seeing Pepe Reina - the man they let go in 2014 - flourishing at Napoli. The Spaniard has become something of a folk hero in Naples and has helped his new club romp to the top of the table, Meanwhile, back at Anfield, there are weekly debates over the merits - or otherwise - of Simon Mignolet and Adam Bogdan.
Daniel Sturridge (Manchester City and Chelsea)
Two blunders for the price of one. First, Manchester City failed to act quickly enough - or persuasively enough - to make Sturridge, a youth academy graduate, sign a new contract in 2009. Then Chelsea could not find a place for him in their regular starting XI, leading to more frustration and a move to Liverpool in 2013. His injury problems notwithstanding, Sturridge has proven himself one of England's best strikers with his performances at Anfield.
Carlos Vela (Arsenal)
One of a clutch of players who promised great things at the Emirates Stadium only for Arsene Wenger to stick with more tried and tested options in his first team squad. Vela wearied of life on the bench and occasional outings in domestic cup competitions, moving to Real Sociedad in 2012. There, he has plundered 43 goals in 119 games and earned regular caps for Mexico.
Romelu Lukaku (Chelsea)
Another Chelsea talent who slipped through the club's fingers. Jose Mourinho never particularly rated the Belgium striker - what is it with him and Belgians? - but Lukaku has gone on to prove his considerable talents with three fine seasons at Everton. Now worth far in excess of the £28million Everton paid for him in 2014.
Gerard Pique (Manchester United)
Pique learned his trade at Manchester United's academy but always pined for a return to his native Barcelona. Could United have done more to keep him? Perhaps, but it was not as if Sir Alex Ferguson was short of options in 2008, when he decided to return. "Pique was a terrific player and I was deeply disappointed when he told us he wanted to move back to Spain," wrote Sir Alex Ferguson in his second autobiography. "Unfortunately he didn't want to wait for Ferdinand and Vidic to fall apart.
Giuseppe Rossi (Manchester United)
The Italian was another foreign academy graduate who found it impossible to progress at Manchester United, making only five appearances between 2004 and 2007. He has since proven his goalscoring abilities at Parma (nine goals in 19), Villarreal (54 in 136) and Fiorentina (16 in 33).