Cardiff City and Swansea City are both keen to strengthen their respective squads this month, albeit for very different reasons.
Swansea, still within touching distance of the top six, will be hoping to bring in the players needed to help strengthen a play-off challenge, while Cardiff are right in the thick of a relegation battle.
Both clubs are understood to have identified targets, although there's a bit of a difference in what they can do in this window.
Cardiff are still held back by the terms of their recent transfer embargo, and still can't pay fees for players, while Swansea are once again working on a tight budget in this window.
As such, Russell Martin will be looking to get as much bang for his buck as possible - and there could yet be some bargains to be found elsewhere in the Championship.
A number of players are out of contract this summer, meaning they could be made available for a cut-price deal. Cardiff, meanwhile, may well have one eye on what might be possible in the summer, although admittedly the will need to ensure they preserve their Championship status first.
Using data from Transfermarkt, here's a full list of every player known to be out-of-contract at the end of the season, including those with the option to extend by a further year, where those options are known.
Birmingham
Maxime Colin, Harlee Dean, Troy Deeney, George Friend, Jonathan Leko, Kevin Long.
One-year option: Nico Gordon, Jordan Graham.
Blackburn
Daniel Ayala, Ben Brereton Diaz.
One-year option: Bradley Dack.
Blackpool
Keshi Anderson, Stuart Moore, Jordan Thorniley.
One-year option: Rob Apter, Liam Bridcutt, Callum Connolly, Kenny Dougall, Luke Garbutt, CJ Hamilton, James Husband, Shayne Lavery, Chris Maxwell, Kevin Stewart, Matty Virtue.
Bristol City
Daniel Bentley, Jay Dasilva, Tomas Kalas, Andy King, Chris Martin, Han-Noah Massengo, Antoine Semenyo, Harvey Wiles-Richards.
One-year option: Timm Klose, Max O'Leary, Antoine Semenyo, Zak Vyner.
Burnley
Ashley Barnes, Johann Berg Gudmunsson, Matthew Lowton, Will Norris.
Cardiff City
Joel Bagan, Mark Harris, Curtis Nelson, Tom Sang, Gavin Whyte.
Coventry City
Kyle McFadzean, Martyn Waghorn, Liam Kelly, Ben Wilson, Marcel Hilssner, Michael Rose, Tyler Walker, Will Bapaga.
One-year option: Fankaty Dabo.
Huddersfield Town
Danny Ward, Florian Kamberi, Josh Koroma.
One-year option: Josh Ruffels, Jon Russell.
Hull City
Greg Docherty, Callum Elder, Josh Emmanuel, Callum Jones, James Scott.
One-year option: Billy Chadwick, Vaughn Covil, Lewie Coyle, Alfie Jones, Tyler Smith.
Middlesbrough
Luke Daniels, Darnell Fisher, Jonny Howson, Tommy Smith, Stephen Walker, Duncan Watmore.
Norwich City
Sam Byram, Todd Cantwell, Kieran Dowell, Onel Hernandez, Jordan Hugill, Michael McGovern, Teemu Pukki, Danel Sinani.
Preston North End
Robbie Brady, Lewis Coulton, Greg Cunningham, Daniel Johnson, Sean Maguire, Matthew Olosunde, Adam O'Reilly.
One-year option: Dana Amaral, Aaron Bennett, Harry Nevin, Ben Woodburn.
QPR
Ody Alfa, Luke Amos, Jordan Archer, Leon Balogun, Conor Masterson, Charlie Owens, Olamide Shodipo.
One-year option: Faysal Bettache, George Thomas, Chris Willock.
Reading
Scott Dann, Nesta Guinness-Walker, Junior Hoilett, Lucas Joao, Shane Long, Amadou Salif Mbengue, Yakou Meite, Liam Moore, Dejan Tetek.
Rotherham United
Dan Barlaser, Wes Harding, Robbie Hemfrey, Chiedozie Ogbene, Lee Peltier, Josh Vickers, Richard Wood.
One-year option: Shane Ferguson, Ben Wiles.
Sheffield United
John Fleck, Wes Foderingham, Kyron Gordon, Oli McBurnie, Oliver Norwood, Jack O'Connell, Ben Osborn, Will Osula, Jack Robinson, Femi Seriki, Billy Sharp, Enda Stevens.
Stoke City
Jack Bonham, Sam Clucas, Frank Fielding, Aden Flint, Morgan Fox, Phil Jagielka, Nick Powell, Mario Vrancic.
Sunderland
Danny Batth, Alex Pritchard.
One-year option: Corry Evans, Ross Stewart.
Swansea City
Joel Latibeaudiere, Ryan Manning, Kyle Naughton.
Watford
Leandro Bacuna, Craig Cathcart, Tom Cleverley, Dan Gosling.
West Brom
Jake Livermore, Erik Pieters, Kenneth Zohore.
One-year option: Tom Rogic.
Wigan Athletic
Ben Amos, Joe Bennett, Jordan Cousins, Tendayi Darikwa, Gwion Edwards, Jamie Jones, Will Keane, James McClean, Max Power, Scott Smith, Curtis Tilt.
One-year option: Ryan Nyambe, Jack Whatmough.
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