Most bookmakers currently have Mayweather (47-0, 26 KOs) at 1/2 and Pacquiao (57-5-2, 38 KOs) at 15/8 to win, which matches up with pundit predictions for the most part. Mayweather's flawless record is largely down to his defensive genius. He's just so hard to hit. Excellent hand speed, accuracy and the ability to adapt to whatever his opponent throws at him make him a formidable opponent.
Mayweather's desire and ability to avoid getting hit is at odds with Pacquiao's ability to throw and often land damaging combinations. That's what makes this a fascinating match up. Some of them are bound to get through, even if Mayweather does display his trademark first class defense. Pacquiao's record in recent years though has some arguing that he's a fighter in decline, so will he be able to land enough to make it count? He does gives it everything and is relentless, so it's all about making those power punches count.
The way I see it, it will likely be an all action encounter, but neither fighter has much of a knock out record over recent years, so I'd expect it to go the distance. As much as I'd like a Pacquiao win, it's hard to see beyond Mayweather's boxing intelligence and hand speed so at 8/11 he's not a bad bet. Make sure you recover the draw though. This is boxing after all.
Bet: Mayweather by Decision or Technical Decision - 8/11 Draw - 20-1