When Jean-Marc Bosman called in the European Court of Justice to settle a dispute between his current employers RFC Liege and future employers Dunkerque in 1995, he changed the beautiful game forever.

The subsequent implementation of the Bosman ruling shifted power into the hands of the players, who previously had no say on whether a club would release them upon the expiration of their contracts and allow them to play somewhere else. Most of the time, they refused to.

At the same time, it also created a new and incredibly cheap sector of the transfer market, where clubs could sign players on 'free transfers' or snap them up a few months early at little cost, with the prospect of losing a player for nothing hanging over the heads of disgruntled chairmen.

Twenty years later, we almost take the Bosman rule for granted. So in honour of its significance, Football Fancast have been running the rule over some of Europe's top stars whose contracts expire at the end of the season.

This article takes a look at FOUR Bosman-bound bargains Premier League outfit Tottenham Hotspur should target in January - to either sign for a nominal fee or enter pre-contract negotiations with.

CHARLIE AUSTIN

Whether you're relegation fodder, title material or somewhere in between, QPR striker Charlie Austin has something to offer.

The 26-year-old was nothing short of phenomenal for Rangers last season, finishing up as the Premier League's fourth-top scorer with 18 goals despite the west London outfit ending the campaign in bottom place.

He's continued to score in the Championship, netting seven in twelve outings thus far, and seems almost certain to return to the top flight in January with Mirror Football claiming QPR will sell for just £8million due to the 6 foot 2 striker's contract expiring at the end of the season.

Of course, Harry Kane remains Spurs' first choice at centre-forward, but Austin would provide some much-needed cover in that department at relatively low cost.

SOFIANE FEGHOULI

A Bosman-bound star reportedly already on Tottenham Hotspur's radar, half of Europe have been linked with Valencia winger Sofiane Feghouli over the last few months.

The Algeria international recorded six goals and six assists in La Liga last season and has continued to impress this term with two strikes in the Champions League, but looks set to leave the Mestalla unless Los Che agree to his demand for a better salary.

Blessed with great pace, power and tricky and now aged 25, Feghouli's game has the potential to jump up a level within the next few years, which is why so many clubs, ranging from Barcelona to Fenerbahce, have taken an interest in his availability.

The Spurs squad could certainly do with another wide man to compete with Heung-Min Son and Erik Lamela. But Valencia are reluctant to sell in January and the Lilywhites could find themselves eclipsed by some of the African attacker's more coveted suitors by the time contract negotiations come around.

NICOLAS N'KOULOU

Spurs are hardly light on centre-backs at the moment and it appears Belgium duo Jan Vertonghen and Toby Alderweireld will be their preferred partnership for the foreseeable future.

But it's hard to look past Nicolas N'Koulou as a fantastic addition in terms of value for money, now that the Cameroonian's Marseille contract is verging upon its final six months.

The 25-year-old has been linked with a Premier League move on countless occasions before without anything materialising, perhaps due to the fact he measures in a little short at 5 foot 11.

But the 63-cap international is long-established as one of the French top flight's best defenders, twice claiming a spot in the Ligue 1 Team of the Season, and has been in good form yet again this year, averaging 1.7 tackles, 2.1 successful aerial duels and 3.9 interceptions per match.

A number of Marseille stars left on free transfers during the summer, namely Andre Ayew and Andre-Pierre Gignac, and it would be unsurprising to see N'Koulou follow suit considering he's been tipped to play at a higher level for some time.

Whether Spurs actually need another centre-half, however, remains open to debate.

Andrija Zivkovic

One of the most exciting prospects outside of Europe's leading top flights available on a free transfer, although a compensation fee would be involved, Andrija Zivkovic has the potential to become one of Tottenham Hotspur's best ever signings.

Indeed, the 19-year-old winger has already claimed 21 goals in 85 appearances for Partizan and consistently improved since his 2013 debut, this season producing nine goals in 19 outings across all competitions. Some have even dubbed him 'The Serbian Messi'.

Having played a pivotal role in Serbia's U20 World Cup triumph earlier this year and also featured for the senior team on three occasions, Zivkovic is almost certain to leave Partizan for a major club when his contract expires in the summer.

Tottenham would be wise to get in on the act but Chelsea are currently viewed as the Premier League's most interested party.