By Alastair Himmer
Kameda's self-predicted reign of terror ended swiftly in his first defense, four months after he captured the belt from countryman Daisuke Naito.
The brash Japanese entered the ring wearing a silver hooded top with purple fur trim to the theme tune from Rocky IV but he failed to live up to his own pre-fight hype.
"I kept calm and the fight went perfectly to plan," Pongsaklek told reporters. "I didn't want to pass the torch to the next generation by losing tonight."
He shook the champion with a fierce uppercut at the start of the 11th and a wincing Kameda almost went down when he was caught by another stinging blow near the end of the final round.
The 32-year-old Pongsaklek was awarded the fight 116-112 and 115-112 by two of the ringside judges with the third surprisingly scoring the contest even at 114-114.
The experienced Thai, who quietly climbed into the ring wearing a simple, red bobble hat in contrast to Kameda's flashy entrance, improved his record to 75-3-1.
Kameda, who was employed as a sparring partner for Pongsaklek while in his teens, tasted defeat for the first time in 23 professional contests.
(Editing by Clare Fallon)
