Jennifer Lopez & Jimmy Fallon Ham It Up During HIGHlarious Dance-Off To '70s Slow Jams -- WATCH!

Jimmy Fallon is giving Jennifer Lopez a run for her money!
The 48-year-old songstress stopped by The Tonight Show on Wednesday night where they went face to face for a “fast dance-off” to ’70s slow jams!
Watch the hilarity (above)!!
[Image via NBC.]