Union Berlin's Bundesliga match at home to bottom side Bochum was suspended for almost half an hour after visiting goalkeeper Patrick Drewes was hit by an object thrown from the crowd.
The 31-year-old German was preparing to take a goal-kick in the second minute of second-half stoppage time, with the score 1-1, when he was struck by what appeared to be a cigarette lighter.
Drewes dropped to his knees and the match was stopped as he received medical attention before referee Martin Petersen suspended the game and ordered both sets of players to the dressing room.
Bochum striker Philipp Hofmann went in goal when play resumed because Drewes was unable to continue and they had already used up their allocation of substitutions.
However, neither side made any attempt to score, passing the ball between themselves as they waited for the full-time whistle to be blown.
Drewes was taken to hospital for checks, the club said.
Hofmann told Sky Germany that both sets of players had "agreed not to play on", saying about the incident that "an action like that just isn't OK at all".
Bochum managing director Ilja Kaenzig said that the club would be appealing against the referee's decision not to abandon the game, arguing they should have been awarded all three points after being left at a "sporting disadvantage".
He said Bochum had only played on "under protest".
"The rules are very clear. We had exhausted our substitution quota," he said.
A Union spokesman said the person responsible for throwing the object "had been identified and handed over to the police".
The club's sporting director Horst Heldt added: "It would be a mistake to blame the whole club or the fans for the action of one individual."
Bochum had Japan midfielder Koji Miyoshi sent off after just 13 minutes of the game but took the lead 10 minutes later through Ibrahima Sissoko.
Benedict Hollerbach scored a first-half equaliser for the hosts but Bochum hung on for just their third point of the season.
They remain winless after 14 games and are nine points from safety, while Union Berlin are 12th on 17 points.