The 2018 World Cup is just a month away and national team bosses are beginning to figure out and finalise the best possible squads to bring to Russia.
In the coming weeks they will be paying close attention to the health of their players because, with plenty of football to be played, injuries will happen, which can throw their plans into disarray.
No footballer - not even the best - is completely invulnerable and sometimes fate can deliver cruel blows to individuals whose talents deserve to be showcased on the world stage. That is simply an unfortunate hazard of the profession.
As well as that, personality clashes, bans and other issues can end up preventing players from taking part.
As 32 teams get set for the big kick-off in June, Goal casts an eye over those stars who are major doubts for the World Cup as well as those who have been ruled out completely.
Confirmed out of World Cup 2018
The question of which players are definitely out of the 2018 World Cup will yield a much clearer answer as we get closer to the tournament in June, with coaches generally keen to give their playing pool the best possible chance of making the final cut. However, the cases of some players missing out are understood, if not officially communicated.
France are hoping to claim their second world title when they compete in Russia this summer but one man who is almost certain not to be part of that journey is Karim Benzema, who has not featured for his country since October 2015. The Real Madrid star does not hold much hope for the prospect of a recall ahead of the World Cup though, explaining his view that he will not be picked as long as Didier Deschamps is head coach.
Laurent Koscielny went down in excruciating pain during Arsenal's Europa League semi-final second-leg defeat to Atletico Madrid after appearing to lose his footing and the club later confirmed that the defender had suffered a torn Achilles tendon. Unfortunately for Koscielny that means his chances of going to Russia as part of the France contingent this summer are now gone and he faces a number of months in recovery.
Dimitri Payet had a memorable Euro 2016 but he's going to be watching from the sidelines for Russia 2018 after picking up a hamstring injury in the Europa League final against Atletico Madrid. The former West Ham United attacker limped off in tears in the first half to end his chances of a call-up from Deschamps, having forced his way into contention with his star performances for Marseille.
Dani Carvajal will endure more heartbreak after an injury in a Champions League final ruled him out of a second successive major international tournament. The Real Madrid full-back missed Euro 2016 after being injured in the final against Atletico Madrid and he suffered a hamstring injury against Liverpool in Kiev to force him out of the World Cup.
England will definitely have to make do without the services of Liverpool midfielder Alex Oxlade-Chamberlain, who suffered a knee ligament injury in the Reds' Champions League semi-final first leg victory over Roma. The former Arsenal star sustained the injury while making a tackle and it comes as a major blow to both the player and Three Lions boss Gareth Southgate.
He will be joined on the sidelines by club-mate Joe Gomez, who had forced himself into contention, and even earned a Man of the Match award during the Three Lions' draw with Brazil having kept Neymar quiet. Ankle surgery, however, has ended his hopes of heading to Russia.
Both Jack Wilshere and Joe Hart have also been excluded from the squad, with Southgate preferring to take Nick Pope instead of the experienced West Ham shot-stopper who has been having a terribly lukewarm season in East London.
Brazil are one of the favourites to win the tournament, but they will have to make do without marauding full-back Dani Alves, who picked up a knee injury during the Coupe de France final and will instead spend the summer recovering ahead of Paris Saint-Germain's 2018-19 campaign.
Germany boss Joachim Low has a massive pool of talent to draw from, but two potential additions to his World Cup panel have been ruled out. Bayern Munich winger Serge Gnabry, who is on loan at Hoffenheim, has been laid low with a groin injury, while Borussia Monchengladbach captain Lars Stindl, who played a key role in the 2017 Confederations Cup win, has suffered a serious ankle injury.
Fernando Gago was part of the Argentina squad that finished runners-up at the 2014 World Cup but he did not make Jorge Sampaoli's final 23 for Russia 2018. Now playing for Boca Juniors and aged 31, the former Real Madrid midfielder suffered a serious knee injury towards the end of 2017 and has thus been left out of the squad. Other notable absentees are Serie A top scorer Mauro Icardi, who was cut from the 35-man shortlist, while Man Utd goalkeeper Sergio Romero has been ruled out through a knee injury.
The likes of Javier Pastore, Angel Correa and Carlos Tevez, meanwhile, were also omitted from the preliminary squad and will play no part in Russia.
There had been vague suggestions - encouraged by the man himself - that Zlatan Ibrahimovic could potentially make a return to the Sweden set-up for the World Cup, but the Swedish FA chief, Lars Richt, has ruled out any such possibility.
More players will undoubtedly join the aforementioned, particularly those who are considered major doubts to make the plane to Russia (see below), and we will keep you updated.
Major doubts for World Cup 2018
Mohamed Salah is a concern for Egypt’s World Cup squad after suffering a shoulder injury in Liverpool’s Champions League final against Real Madrid. The forward left the pitch in tears in the first half in Kiev after being hauled to the ground by Sergio Ramos.
Five-time winners Brazil head to the tournament as one of the favourites but one of their star players finds himself in a desperate race to recover full fitness in time for the kick-off. Neymar underwent surgery on his foot in March after suffering a fractured metatarsal and a sprained ankle while playing for Paris Saint-Germain. The expectation is, however, that he'll be ready to feature for his country in their warm-up clash with Croatia on June 3.
Germany could have been forced into a defensive reshuffle following the news of Jerome Boateng's thigh injury, which has brought his domestic season to a premature end. The Bayern Munich centre-back had been expected to be out of action for between four and six weeks but he has been included in his country's provisional squad and appears likely to be ready for Russia.
Despite Michy Batshuayi's domestic season ending prematurely due to an ankle injury, he has made Belgium's World Cup squad wich was announced on May 21.
Iceland will be taking part in the World Cup for the first time in their history and Everton midfielder Gylfi Sigurdsson will be involved. A knee ligament injury in March had cast serious doubts over his availability for the tournament in June but he was named as part of manager Heimir Hallgrimsson's squad and looks all set to ready to feature in Russia.
Peru's Paolo Guerrero looks almost certain to miss the World Cup after seeing his doping ban extended to 14 months by Court of Arbitration for Sport (CAS). FIFPro are in the process of appealing to FIFA that he should be allowed to play, however, having previously tested positive for performance-enhancing drugs.
Potential doubts for World Cup 2018
While Manuel Neuer has been named in Germany's provisional squad, the Bayern Munich keeper will be assessed further before Joachim Low makes his final call on the 23 players who will feature in Russia. Low said at a press conference on May 15: "We want to see for ourselves if Manuel Neuer is fit, we have a chance to see and assess him. And after the training camp we want to talk fair and square."