Poland striker Robert Lewandowski was felled by a firework thrown from the crowd in a stormy World Cup clash on Friday but he had the last laugh, scoring twice in a 3-0 win over Romania.
Romanian fans threw the firework at the Bayern Munich star in the 53rd minute.
He needed medical treatment while referee Damir Skomina gathered the players from both sides inside the penalty area.
The second half incident could see a stiff UEFA punishment for the Romanians, who slumped to a 3-0 loss which saw the Poles go top of the pool.
Kamil Grosicki had notched an early opener before Bayern Munich’s Lewandowski had the last laugh with two late goals.
After play was briefly delayed, Lewandowski recovered to hit two late goals after 84 minutes and a last-gasp penalty.
On the terraces, fans from both countries launched flares at one another. Some thrown by home fans landed on the pitch, causing a delay just before the half-time mark.
Twelve Polish fans had already been arrested before the game after fighting in a city centre bar and clashes with police outside the stadium.
Around 4,000 police were mobilised for the high-risk game. Bucharest police have questioned 17 football fans after clashes on Friday.
Police said 12 Poles and five Romanians were taken for questioning, with 12 fined for the clashes. The nationalities of the 12 fined were not disclosed.
Alis Grasu, a spokeswoman for the ambulance service, said a Pole with stomach pains and a Romanian with a heart condition were hospitalized. Neither condition was life-threatening.