Poland's World Cup qualifier against Romania was halted for close to 10 minutes after Robert Lewandowski was almost struck by what appeared to be a flare thrown from the crowd.
The object exploded close to the Bayern Munich striker as Poland were preparing to defend a corner in the second half in Bucharest.
Friday's game was paused for several minutes as Lewandowski received treatment, after going to ground holding his face.
The incident was one of a number to mar the encounter, with another flare reportedly having burned part of one of the goal nets, while some rival supporters clashed in the stands.
The 28-year-old later struck a second goal for Poland following Kamil Grosicki's first-half opener, before converting a penalty in injury time to secure his side's 3-0 win.
The victory moved Poland to the top of Group E, three points ahead of Montenegro, who surrendered a 2-0 lead to lose 3-2 to Armenia earlier on Friday.