Robert De Niro will show off his new film “Grudge Match” with Sylvester Stallone at the annual Tribeca Film Institute benefit on Monday before its Christmas Day release. And we hear the stars will show off their boxing moves on the red carpet. A spy says there will be punching bags on the carpet and at the party, at the Ziegfeld Theater and Skylight at Moynihan Station. The movie stars Tribeca co-founder De Niro as a boxer who comes out of retirement to battle Stallone 30 years after their in-the-ring rivalry ended. Dinner will be served, in part, from food trucks at the Skylight party space — with grub from Red Hook Lobster Pound, Phil’s Steaks, J-Dogs, Go Burger and Baked by Melissa, among many others. Guests expected to chow down and hit the bags besides De Niro and Stallone include Kim Basinger, Kevin Hart, Alan Arkin, gala co-chairs Ron Burkle, Raphael De Niro, Katharina Otto-Bernstein and Nathan Bernstein, and Tribeca partner Jane Rosenthal.