The deadline for clubs to submit their updated squad lists for the Champions League and Europa League passed at 00:00 CET on Thursday night.
Clubs had a day after the January transfer window closed to get their new signings onto the list for the knockout phase of this season's European competitions.
Some players, like Alexis Sanchez and Olivier Giroud, are eligible to play in the Champions League for Manchester United and Chelsea respectively despite having already featured in the Europa League for Arsenal this season. However others, like Pierre-Emerick Aubameyang, are cup-tied for the remainder of the season in Europe.
Here are the squad lists for the biggest clubs left in the the knockout phase of the Champions League and Europa League.
ARSENAL: Arsenal surprisingly included Santi Cazorla in their Europa League even though the Spanish midfielder is still expected to miss the rest of the season. Cazorla was one of three additions in Arsenal's squad for the knockout stages along with newcomers Henrikh Mkhitaryan and Konstantinos Mavropanos. There was plenty of room for Cazorla as no fewer than 12 players have been dropped from the list that was submitted to UEFA for the group stages. Arsenal sold five players in January and sent a number of their youngsters out on loan. Pierre-Emerick Aubameyang, who became the club's record signing on Wednesday, isn't eligible for the competition after appearing for Borussia Dortmund this season. -- Mattias Karen
Squad: Petr Cech, David Ospina, Matt Macey, Deyan Iliev; Per Mertesacker, Laurent Koscielny, Rob Holding, Nacho Monreal, Shkodran Mustafi, Calum Chambers, Hector Bellerin, Konstantinos Mavropanos, Sead Kolasinac; Aaron Ramsey, Jack Wilshere, Mesut Ozil, Alex Iwobi, Santi Cazorla, Granit Xhaka, Mohamed Elneny, Henrikh Mkhitaryan; Alexandre Lacazette, Danny Welbeck
ATLETICO MADRID: Atletico Madrid have added Diego Costa and Vitolo to their squad for their forthcoming Europa League campaign, with the pair now free to be registered with the club they joined last summer, when the Rojiblancos were starting out the season in the Champions League. Luciano Vietto and Augusto Fernandez, now at Valencia and Beijing Renhe, are the players to drop out. Out of favour playmaker Nico Gaitan is still included, although he may still leave for a country where the transfer window remains open, such as China or Russia.
BARCELONA: Barcelona are unable to add club record signing Philippe Coutinho to their Champions League squad because he is cup-tied having played in the competition with Liverpool already this season. The Brazilian will have to wait until next season to grace the European stage with his new team. Defender Yerry Mina, a January signing from Palmeiras, does come into the squad, though, as Javier Mascherano, Arda Turan, Rafinha and Gerard Deulofeu are unregistered. All four left the club, either on loan or permanently, last month.
BAYERN MUNICH: Bayern's captain Manuel Neuer hasn't played since September after fracturing his foot and is still on the comeback trail --unlikely to return in time to face Besiktas in the Champions League round of 16 either. However, Bayern's No. 1 will be named in the squad with the expectation that he is fit for the business end of the competition after the Turkish champions are (hopefully) disposed of. New signing Sandro Wagner comes in too as back-up striker for top scorer Robert Lewandowski, who was crucially injured during last season's quarterfinal loss to eventual winners Real Madrid. -- Mark Lovell
DORTMUND: Michy Batshuayi, Marco Reus and Jadon Sancho are all included in Borussia Dortmund's Europa League squad, but defender Manuel Akanji misses out on a place. UEFA regulations allow clubs to register three new players for the knockout rounds of the competition, but only one can have been fielded in a UEFA club competition group stage match for another club. That meant BVB had to choose between on-loan Chelsea striker Batshuayi and Akanji, signed from Basel, who had both played in the Champions League this season. -- Stephan Uersfeld
Squad: Roman Weidenfeller, Domink Reimann, Roman Burki; Dan-Axel Zagadou, Raphael Guerreiro, Jeremy Toljan, Sokratis Papastathopoulos, Lukasz Piszczek, Marcel Schmelzer, Omer Toprak, Erik Durm; Nuri Sahin, Marco Reus, Sebastian Rode, Mahmoud Dahoud, Shinji Kagawa, Gonzalo Castro, Julian Weigl; Jadon Sancho, Adnriy Yarmolenko, Mario Gotze, Alexander Isak, Maximilian Philipp, Andre Schurrle, Michy Batshuayi.
CHELSEA: Unsurprisingly all three January signings have been added to Chelsea's squad list for the Champions League knockout stage, with Olivier Giroud replacing Michy Batshuayi, Kenedy making way for Emerson Palmieri and Ross Barkley filling the space created by Charly Musonda's 18-month loan move to Celtic. The only notable omission is Ethan Ampadu, who does not qualify for the B list reserved for youth players because he only signed for Chelsea from Exeter City last summer. -- Liam Twomey
Squad: Thibaut Courtois, Willy Caballero, Eduardo; Antonio Rudiger, Marcos Alonso, David Zappacosta, Gary Cahill, Andreas Christensen, Cesar Azpilicueta, David Luiz; Emerson Palmieri, Dujon Sterling, Cesc Fabregas, Danny Drinkwater, N'Golo Kante, Ross Barkley, Eden Hazard, Pedro Rodriguez, Tiemoue Bakayoko, Vicotr Moses, Willian, Kyle Scott; Alvaro Morata, Olivier Giroud, Callum Hudson-Odoi.
JUVENTUS: Juventus has left Germany internationa Benedikt Howedes out of the UEFA players' list, while Switzerland captain Stephan Lichtsteiner returns to the squad. Juve haven't brought anyone new to the club in January, so this is the only change. -- Jonathan Shkurko
Squad: Gianluigi Buffon, Mattia De Sciglio, Giorgio Chiellini, Mehdi Benatia, Miralem Pjanic, Sami Khedira, Juan Cuadrado, Claudio Marchisio, Gonzalo Higuain, Paulo Dybala, Douglas Costa, Blaise Matuidi, Alex Sandro, Andrea Barzagli, Carlo Pinsoglio, Mario Mandzukic, Kwadwo Asamoah, Wojciech Szczesny, Daniele Rugani, Stephan Lichtsteiner, Stefano Sturaro, Rodrigo Bentancur, Federico Bernardeschi.
LIVERPOOL: There's a boost for Liverpool as Nathaniel Clyne has been included in Jurgen Klopp's squad for the knockout rounds of the tournament. Clyne hasn't played at all this season due to a back injury and was excluded from Liverpool's squad list in the group stages, with Joe Gomez and Trent Alexander-Arnold deputising in the right-back spot. Virgil van Dijk and Danny Ings have also been added to the squad, while January departures Philippe Coutinho, Daniel Sturridge, Marko Grujic and Jon Flanagan have been removed. -- Glenn Price
Squad: Simon Mignolet, Loris Karius, Danny Ward; Nathaniel Clyne, Trent Alexander-Arnold, Joel Matip, Dejan Lovren, Joe Gomez, Ragnar Klavan, Virgil van Dijk, Alberto Moreno, Andrew Robertson, Conor Masterson; Georginio Wijnaldum, James Milner, Jordan Henderson, Adam Lallana, Alex Oxlade-Chamberlain, Emre Can; Roberto Firmino, Dominic Solanke, Danny Ings, Mohamed Salah, Sadio Mane, Ben Woodburn, Rhian Brewster.
MAN CITY: Pep Guardiola has added two new faces to his Champions League squad with club-record signing Aymeric Laporte replacing Eliaquim Mangala, who has left on loan. Ukrainian Oleksander Zinchenko has emerged as a backup left-back in the absence of injured duo Benjamin Mendy and Fabian Delph and a space was freed up for him by third-choice goalkeeper Arijanet Muric now qualifying as a homegrown player. -- Jonathan Smith
Squad: Claudio Bravo, Ederson, Ajijanet Muric; Danilo, Vincent Kompany, Aymeric Laporte, Benjamin Mendy, Nicolas Otamendi, John Stones, Kyle Walker, Tosin Adarabioyo; Fabian Delph, Kevin De Bruyne, Fernandinho, Ilkay Gundogan, Leroy Sane, Raheem Sterling, Bernardo Silva, David Silva, Yaya Toure, Phil Foden, Brahim Diaz; Sergio Aguero, Gabriel Jesus, Lukas Nmecha.
MAN UNITED: Manchester United have registered Alexis Sanchez for the Champions League knock-out rounds following his move from Arsenal. It means the Chilean will be eligible to face Sevilla in the last-16 when the competition restarts this month. Zlatan Ibrahimovic remains on the list despite speculation he could move to LA Galaxy before the end of the season. James Wilson has been omitted after his loan move to Sheffield United but Axel Tuanzebe and Demetri Mitchell have been included despite signing temporary deals at Aston Villa and Hearts, respectively. -- Rob Dawson
Squad: David De Gea, Sergio Romero, Joel Pereira*, Kieran O'Hara; Victor Lindelof, Eric Bailly, Phil Jones, Marcos Rojo, Chris Smalling, Daley Blind, Luke Shaw, Antonio Valencia, Matteo Darmian, Axel Tuanzebe; Paul Pogba, Juan Mata, Jesse Lingard, Michael Carrick, Ashley Young, Ander Herrera, Marouane Fellaini, Nemanja Matic, Demetri Mitchell*, Scott McTominay; Alexis Sanchez, Romelu Lukaku, Zlatan Ibrahimovic, Anthony Martial, Marcus Rashford.
PSG: Paris Saint-Germain's Champions League squad is largely unchanged for the latter stages. New signing Lassana Diarra has replaced now Tottenham Hotspur man Lucas Moura in the only major alteration to the list. Otherwise, youth academy product Sebastien Cibois has replaced Remy Descamps as third-choice goalkeeper. Hatem Ben Arfa remains out of the squad after he was unregistered during the group phase. Although now on loan with different clubs, UEFA have included Alec Georgen (AZ Alkmaar) and Moussa Diaby (Crotone) as part of PSG's B list. Cibois, Garissone Innocent, Stanley N'Soki, Loic Mbe Soh, Lorenzo Callegari and Antoine Bernede are also among those players who, if needed, could also step up to the senior squad. -- Jonathan Johnson
Squad: Kevin Trapp, Alphonse Areola, Garisonne Innocent, Sebastien Cibois; Thiago Silva, Presnel Kimpembe, Marquinhos, Thomas Meunier, Yuri Berchiche, Layvin Kurzawa, Alec Georgen, Dani Alves, Loic Mbe Soh, Stanley Nsoki; Marco Verratti, Thiago Motta, Angel Di Maria, Giovani Lo Celso, Lassana Diarra, Julian Draxler, Christopher Nkunku, Adrien Rabiot, Javier Pastore, Lorenzo Callegari, Antonio Bernede, Moussa Diaby; Edinson Cavani, Neymar, Kylian Mbappe.
REAL MADRID: Real Madrid go forward into the Champions League knockout rounds with the same squad that finished second in their group behind Tottenham last autumn, after coach Zinedine Zidane made clear that despite their difficult 2017-18 to date he did not have any "quick fix" solutions in the transfer market, and wished to give the squad a chance to return to the performance levels which have seen them win three of the last four European trophies.
TOTTENHAM: Deadline day signing Lucas Moura and Erik Lamela have been added to Tottenham's Champions League squad, with Juan Foyth and Georges-Kevin Nkoudou dropping out. Spurs have a full quota of 17 overseas players so 19-year-old centre-back Foyth and Nkoudou, who has joined Burnley on loan for the rest of the season, have been omitted from the 21-man senior group. Moura is not cup-tied having not played in the Champions League for Paris Saint-Germain this season, while the injured Lamela was omitted from the original squad but returned from a 13-month injury absence in November. -- Dan Kilpatrick
Squad: Hugo Lloris, Michel Vorm, Paulo Gazzaniga, Alfie Whiteman; Kieran Trippier, Danny Rose, Toby Alderweireld, Jan Vertonghen, Davinson Sanchez, Serge Aurier, Ben Davies, Kyle Walker-Peters, Erik Lamela, Victor Wanyama, Eric Dier, Moussa Sissoko, Moussa Dembele, Dele Alli, Christian Eriksen, Lucas Moura, Harry Winks, Luke Amos, Anthony Georgiou, Tashan Oakley-Boothe, Son Heung-Min, Fernando Llorente, Kazaiah Sterling, Harry Kane.