Former Mayor Rudy Giuliani threw a curveball at contractors who installed a new fence around City Hall Park 10 years ago by ordering them to finish in time for one of his beloved Yankee parades, the contractors charge.

Skanska USA and subcontractor Maspeth Welding have been locked in a legal fight with the city, which sued them in 2004 after granite at the fence’s base cracked.

They say it’s the mayor’s fault because he insisted on a rush job.

The city “said bring the rails [for the fence], we got to get them up in any condition prior to the [1999] parade,” said Maspeth Welding boss Jeffrey Anscholowar.

The city claims the contractors made “fatal errors” such as failing to use sealant.