Workers at Rio de Janeiro’s two airports declared a partial work stoppage beginning at midnight on Wednesday, on the eve of the opening match of the World Cup. A subway strike that threatened to disrupt the opening of the World Cup was also averted on Wednesday night.

Rio’s Galeao international airport is expected to be one of the country’s busiest during the month-long soccer tournament. The walkout also would affect Santos Dumont airport, which provides domestic service, including flights to Sao Paulo, where the first World Cup game was being held on Thursday.

Unions representing workers at the two airports including check-in counter clerks, baggage handlers and janitorial staff have been seeking for months raises of at least 5.6 percent and special bonuses tied to the World Cup.

A union representative said only 20 percent of workers would walk off the job for 24 hours initially. The official agreed to discuss specifics of the walkout only if not quoted by name because he wasn’t authorized to speak publicly.

A labour court in Rio issued an injunction ordering the unions to maintain staffing at 80 percent of normal levels or face fines of up to $22,400.