Carmelo Anthony is the single greatest Olympic basketball player in history ... so says his Knicks teammate Brandon Jennings ... who says Melo is no doubt the international GOAT.

We got Brandon out in L.A. Sunday and asked about Anthony taking home his record-breaking 3rd gold medal ... and if it puts him ahead of other greats who've donned the red, white, and blue.

Brandon says Melo has done more than enough to prove he's the MAN on the world's biggest stage.

One thing's for sure ... Michael Jordan is gonna be annoyed by this.

Oh, and get this ... Jennings also explains why he has ZERO desire to play for Team USA.