Poland midfielder Grzegorz Krychowiak scored a goal but made a costly error as Senegal began their World Cup campaign with victory on Tuesday.
With Senegal ahead through a first-half own goal by Thiago Cionek, Krychowiak played a high, aimless backpass that striker M'Baye Niang controlled ahead of goalkeeper Wojciech Szczesny before tapping into an empty net.
Krychowiak pulled a goal back in the 86th minute with a header from Kamil Grosicki's free-kick but Senegal held on, reports BBC.
Poland are the highest-ranked side in Group H at number eight in the world, but struggled to create further chances with a free-kick from captain Robert Lewandowski one of just four shots on target.
Senegal, making only their second World Cup appearance, join Japan - who beat Colombia earlier on Tuesday - on three points at the top of the group.