Franck Ribery was hit in the face with a scarf by a spectator as holders Bayern Munich beat Hamburg 3-1 to reach the last 16 of the German Cup.
The midfielder, back after a long injury layoff, scored Bayern's third before a fan ran on to the pitch and confronted him late on.
"Fortunately, nothing much happened,'' Ribery told German television.
Robert Lewandowski and David Alaba also scored for Bayern. Pierre-Michel Lasogga headed in a late consolation.
Bundesliga leaders Bayern are unbeaten in the league and Champions League this season, and they took an early lead in this game when forward Lewandowski fired in a rebound after an error by Hamburg defender Heiko Westermann.
Alaba's long-distance shot on the stroke of half-time caught out home goalkeeper Jaroslav Drobny to put Pep Guardiola's side in control.
Ribery, back after a long injury layoff, wrapped up the win with a deflected strike.
Bayern play Borussia Dortmund in the Bundesliga this weekend, before facing Roma in the Champions League next week.