The soccer legend went on "The Late Late Show With James Corden" and proved there's a lot of walk behind all his talk -- nailing a perfect floss dance right on cue.

In fact ... Corden was so impressed -- he wanted some lessons!!!

So, what was the reason for the night-time dance party?? James needed to figure out if Zlatan really CAN do anything.

The first test? Name three Kardashians.

The second test? Open a jar of pickles.

The third test? Hit the floss.

Done, done and BIG-TIME done.

Then, for good measure, he pronounced his full name with a mouth full of marshmallows. Impressive.