The incident happened late in the second set when a sheet of metal, attached to a giant video screen and scoreboard, fell from high above the main Philippe Chatrier Court.
One man was seen being led away holding his head and arm as the court was buffeted by gusts reaching speeds of up to 40 km/h. The match was suspended for around 30 minutes as fans were cleared away from the danger area.
Photographs showed the piece of metal to be around six metres long with spikes on one side, suggesting it was used to keep pigeons away from the huge screen, one of two positioned at opposite corners of the 14,911-capacity arena.
The incident which occurred around 1500GMT is the latest to embarrass organisers of the French Open at the historic Roland Garros stadium.
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On the opening day, there was a major security worry when a spectator leapt from the VIP boxes on the sidelines of the showpiece Philippe Chatrier arena to grab a 'selfie' with Roger Federer as the Swiss star left the court.
"I am not happy about it. Normally I only speak on behalf of myself, but in this situation I think I can speak on behalf of all the players, that that's where you do your job, that's where you want to feel safe," said Federer.
In a match between Fabio Fognini and Benoit Paire on Court Seven, a fight even broke out between fans.