After narrowly missing out on promotion to the Premier League last season, Middlesbrough will be keen to keep hold of top spot in the Championship for the rest of the 2015-16 season.

The league leaders sit two points clear of second-placed Hull City with a game in hand and the best defensive record in the division.

Aitor Karanka's side have been linked with numerous attacking players in this window, including Blackburn striker Jordan Rhodes and Ross McCormack of Fulham, both of which could command the highest transfer fee in the Championship in this window.

If Boro do sign the duo, they'll likely need to look to the free agent market for any further signings.

Athletic Bilbao striker Kike Sola is the only addition at The Riverside so far this month, with the striker coming in on loan for the rest of the season.

FootballLeagueWorld looks at THREE free agent options available to Middlesbrough this month........

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PRESS THE IMAGE BELOW TO SEE THE 3 FREE AGENTS!

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Georgios Samaras

Samaras

The former Celtic and Manchester City striker has been looking for a new club since his West Bromwich Albion contract was cancelled by mutual consent in the summer.

It's been widely reported that the Greek international has had some fitness problems since then, failing a medical with Italian side Sampdoria before rehabbing a back injury with the New York Cosmos.

Samaras, who has occasionally been used as a winger as well as a forward, can score goals as well as create them, netting 53 times in 172 league appearances during his time with Celtic.

A player with title-winning experience who has played in the Champions League and Premier League would be incredibly useful to a side looking to end a seven-season absence from the top flight, while strengthening an attack that has relied on the defence doing its job too often.

Niko Kranjcar

Niko Kranjcar

Croatian Niko Kranjcar certainly knows what it takes to win promotion to the Premier League, having done so through the play-offs with QPR in the 2013-14 campaign.

While some free agent signings will need a couple of weeks to get up to match fitness, the midfielder should be ready to go, having only been released by Dynamo Kiev last week.

Boro haven't been the highest-scoring side in the division in recent weeks, but the 31-year-old would definitely strengthen the attack with his long-range shooting and direct free kick threat.

Former Real Madrid assistant Karanka should be familiar with Kranjcar, as the midfielder played for Spurs when the London side faced the Spanish side in the Championship league in 2011.

Kevin Constant

kevin constant

Kevin Constant has been looking for a new home since coming to the end of his deal with Trabzonspor in the summer, and has already been linked with a move to the Championship.

QPR are thought to be keen to sign the 28-year-old Guinea international, but the chance to join a side in the promotion race would surely tempt the left-back, who can also play in midfield.

Boro certainly don't need a left-back, with George Friend putting in consistently excellent performances, but James Husband's loan with Huddersfield could leave the league leaders vulnerable in the event of injury at the back.

The option to pick up a capable and experienced deputy for free must be tempting, with Constant being a highly-rated passer of the ball, cross blocker and direct free kick-taker, who has also spent time with AC Milan, Toulouse and Genoa.

Middlesbrough fans...What do you make of these players? Do you think they could help the club clinch promotion? Let us know your thoughts and opinions in the comments below!