The injured beast inadvertently attracted the predator with his loud calls for help when the pride of lions attacked him in Kruger National Park, South Africa.
The hyena soon arrived to see if it could finish what the Lions had started.
But the bull was too strong to bring down so the hyena made do with biting his testicles before scurrying off.
Sian Green, a freelance guide, told latestsightings.com: 'This old buffalo bull, generally known as a 'dagga boy', was exhausted after a long fight with a pride of lions.
'When buffaloes are under attack by predators, they make a call, so as to attract back-up from a nearby herd. But, dagga boys are solitary, mostly, and so the calls usually end up alerting other predators of the attack.
A very brave hyena must have heard the commotion and came to see what was going on.
'The hyena could probably see that the buffalo was still in shock, and so while the buffalo was so exhausted, the hyena sneaks from behind sees an opening and grabs on to the buffalo's balls!'
'The buffalo is obviously in shock and in pain and quickly reacts to escape the hyena's hold.
'The buffalo must have had some good practice with fighting off the lions, and managed to fight off the hyena too.'
-Dailymail