Bucks star Giannis Antetokounmpo terrifyingly hyperextended his knee Tuesday -- with his leg violently snapping backward mid-game -- and there's now big concern the Greek Freak could be SERIOUSLY injured.
The 26-year-old 2-time NBA MVP crumpled to the floor in pain during the 3rd quarter of Milwaukee's playoff game against the Atlanta Hawks -- and replays of the injury were tough to watch.
As Giannis was going up to try to block a shot, he landed awkwardly on his left leg .