Spider-Man STREET BALLIN' in NYC -- Is that Andrew Garfield??

Spider-Man sucks at defense ... at least, that's the way it seemed when the superhero took on a couple of kids on a blacktop court in NYC recently -- but the million dollar question ... was that Andrew Garfield??

The footage just surfaced on YouTube -- and appears to be shot right near the Spider-Man movie set in New York.

In fact, you can hear people in the background getting excited when someone tells them the masked baller is actually Andrew, who never reveals his face.

Oh ... and according to SportsGrid, the person who uploaded the clip to YouTube says the blonde chick with the dog is Emma Stone.