Subway workers have entered the fourth day of a strike that has interrupted service at more than 30 stations in the city that hosts the World Cup opening match on Thursday.

Sao Paulo's metro system workers are demanding a salary increase of more than 12 percent, but the company says that kind of raise isn't possible because fares haven't gone up in the past two years.

A labor court is ruling on Sunday on whether the strike is legal.

Authorities were forced to work in a resolution this weekend because the soccer tournament is only days away. The union has threatened to continue the strike, opening the possibility for transit chaos and making it difficult for soccer fans to reach the stadium.