The 26th-ranked Fish converted all four of his break points against Darcis. Fish will play Richard Gasquet of France in the second round.
Lucky loser Simone Bolelli also advanced, beating Nicolas Almagro of Spain 7-6 (4), 6-1. The Italian will next face U.S. Open finalist Andy Murray.
Gilles Simon of France saved three match points before beating Igor Andreev of Russia 4-6, 6-1, 7-6 (7).
Top-ranked Rafael Nadal, who won in Madrid three years ago and is looking for his fourth Masters title of the season, will play Ernests Gulbis of Latvia on Tuesday. Roger Federer opens against Radek Stapenek of the Czech Republic on Wednesday.
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