It is often said that one player does not make a team, and few in football would argue otherwise. Nonetheless, the frantic bartering during last month’s transfer window reflected the reality that an individual can often make all the difference.

That is why, while many clubs opted to postpone their buying and selling until the close season, plenty of others used January to bring in players in the hope of immediate reward. And there is ample historical evidence to justify this aspiration, from mid-season signings who provided the inspiration behind a title surge to those who saved their new employers from seemingly inevitable relegation.

King Eric conquers England
Of all the examples, Eric Cantona is perhaps the most compelling. After all, the charismatic Frenchman was the subject of two pivotal mid-season transfers – both within the space of a single calendar year. The first, in February 1992 - after he was turned down by Liverpool - was to Leeds United, whom he promptly helped to their first top flight title since 1974.

Nine months later, Sir Alex Ferguson – having missed out on previous targets Brian Deane, David Hirst and Matthew Le Tissier – made a speculative enquiry about Cantona’s availability. To his astonishment, Leeds were prepared to do business and, for the paltry sum of £1.2million, the Red Devils acquired one of their all-time greats. Cantona’s impact was spectacular. United, without a championship since 1967 and seemingly out of the title race, made a dramatic late charge, ultimately finishing ten points clear of their closest challengers. By the time Cantona bid adieu five years later, he had won nine major trophies, and was later named the Premier League's Overseas Player of the Decade.

While ‘King Eric’s’ 1992 deals take some beating, an equally impressive example of the impact one signing can make had been provided two decades earlier. The subject of that particular deal was Johan Cruyff, who joined Barcelona in 1973 for a then record fee of £1million following a fall-out at Ajax over the club captaincy. When he arrived, Barça were bottom of La Liga; by the end of the same season, they had been crowned champions for the first time since 1960. No wonder the club’s fans dubbed the Dutch master ‘El Salvador’ (The Saviour). For Ajax, meanwhile – European champions in each of the previous three seasons – the same transfer signalled the beginning of the end for a truly golden era.

A momentous mistake
Barça might have been the beneficiaries in this exchange, but not every mid-season transfer has worked out to their advantage. In September 1953, they came out on the wrong side of an acrimonious tug-of-war with Real Madrid, one which culminated in a decision that would haunt them for decades. At the time, both clubs claimed to have agreed a deal to sign Alfredo di Stefano from Millonarios and, in adjudicating, the Spanish football authorities decreed that the player would turn out for Real during the 1953/54 season before switching to Barça for the following campaign.

The Catalans, though, were unhappy with this compromise and, having received reports of Di Stefano’s unimpressive early showings at the Bernabeu, sold their share of the transfer rights to Real for a nominal fee. The folly in that decision was quickly revealed, as they were beaten just days later thanks largely to a Di Stefano hat-trick. And the rest, of course, is well-documented history, with Real’s ‘Saeta Rubia’ (Blond Arrow) leading the club out of their great rivals’ shadow and onwards to an unparalleled era of success, during which Di Stefano himself won eight league titles and five European Cups.

Around the same era, in December 1961, another historic mid-season transfer saw Tottenham Hotspur part with a British record fee of £99,999 to end Jimmy Greaves’ short-lived spell at AC Milan. A hat-trick on his debut proved an indication of what was to come, with this supreme predator going on to score 266 goals to set a club record that stands to this day.

While Di Stefano and Greaves offer lessons from the past, one club in Germany provides a more current example of just how important mid-season trading can be. In January of last year, Borussia Monchengladbach were rock bottom of the Bundesliga and seemingly destined for relegation, having won just two of their opening 17 matches, conceding a league-high 47 goals in the process. That they survived, and are currently one point off the summit, with the best defence in Germany, can be attributed to several factors, but none were more influential than the arrival last January of defensive duo Martin Stranzl and Havard Nordtveit.

Relegation saviours and returning heroes
Plenty of other mid-season signings have become beloved for preserving their clubs’ top-flight status. Ivica Olic’s goals in 2007 were crucial to Hamburg’s Bundesliga survival, for example, while Birmingham City fans still remember Christophe Dugarry fondly for his classy contribution to their successful fight against relegation in 2003. And David Unsworth’s role in Wigan Athletic’s final-day reprieve in 2007 was deliciously ironic, with the defender scoring the goal that not only saved his new team, but consigned Sheffield United, the club that had sold him, to the dreaded drop.

Enduring tough times while a discarded former player thrives is not unique to the Blades. In China, for example, Bayi FC lived to regret selling Hao Haidong to Dalian Shide in 1996. As Bayi, top-three finishers in the season before, began an inexorable slide towards relegation, Hao excelled, winning five national titles with Dalian and finishing top scorer on four occasions. The country’s current champions, Guangzhou Evergrande, also owed much of their success to an influential mid-season arrival, with Dario Conca having scored nine times in 14 appearances during the second half of the club’s triumphant and historic Super League campaign.

In South America, meanwhile, homecomings have tended to yield the most memorable results. Rai was already a hero at Sao Paulo when he returned from Paris Saint-Germain in between the club’s two legs of the 1998 Campeonato Paulista final against Corinthians. He had barely trained, and some feared a tarnishing of his legend. But they need not have worried. With 30 minutes played, and the aggregate score locked at 0-0, Rai headed in the opening goal that propelled Sao Paulo to a 3-1 win and their first state title in four years.

Such fairy tales have become the stuff of legend, and while they remain few and far between, all offer hope to the coaches and chairmen who spent January on the hunt for a hero.