The stumbling block in the most-awaited boxing fight in recent history, the planned Manny Paquiao vs. Floyd Mayweather, Jr., has been the insistence of Mayweather’s camp and the refusal of Manny Paquiao to undergo Olympic-style drug testing which requires blood testing and not just urine testing. What really is the difference? Read urine testing vs. blood testing in Paquiao vs. Mayweather at Pinoy Seminars.