Poland's preparations for this month's World Cup suffered a blow on Monday after defender Kamil Glik seriously injured his shoulder in training on the same day as being named in head coach Adam Nawalka's 23-man squad for the tournament in Russia.
Nawalka had already submitted his squad list to FIFA before the incident with Glik which happened when the AS Monaco man fell awkwardly after attempting an overhead kick.
The Poland coach said that should the 30-year-old not recover in time to travel to Russia, he would be replaced by VfB Stuttgart's Marcin Kaminski.
World Cup rules allow the final squad to be named 24 hours before the first game starts.
"If it turns out, with 100 percent certainty, that Kamil is not able to play this will be a big loss for for our team," Poland captain Robert Lewandowski told the private TVN24 broadcaster. "On the other hand, we cannot give up, we cannot break down, we have to continue to fight and think everyting will be fine."
Poland play Senegal on June 19 before facing other Group H opponents Colombia and Japan.
Prior to the World Cup, Poland play friendly warm-up matches against Chile on Friday and Lithuania next Tuesday.
Poland's 23-man squad:
Goalkeepers: Bartosz Bialkowski (Ipswich Town), Lukasz Fabianski (Swansea), Wojciech Szczesny (Juventus)
Defenders: Jan Bednarek (Southampton), Bartosz Bereszynski (Sampdoria), Thiago Cionek (SPAL), Kamil Glik (AS Monaco), Artur Jedrzejczyk (Legia Warszawa), Michal Pazdan (Legia Warszawa), Lukasz Piszczek (Borussia Dortmund)
Midfielders: Jakub Blaszczykowski (VfL Wolfsburg), Jacek Goralski (Ludogorets Razgrad), Kamil Grosicki (Hull City), Grzegorz Krychowiak (West Bromwich Albion), Rafal Kurzawa (Gornik Zabrze), Karol Linetty (Sampdoria), Slawomir Peszko (Lechia Gdansk), Maciej Rybus (Lokomotiv Moscow), Piotr Zielinski (Napoli)
Forwards: Dawid Kownacki (Sampdoria), Robert Lewandowski (Bayern Munich), Arkadiusz Milik (Napoli), Lukasz Teodorczyk (Anderlecht). (Reporting by Anna Koper Editing by Agnieszka Barteczko and Christian Radnedge)