Floyd's ring smarts will stand to him
Both are exceptionally quick, but in different ways. Mayweather's reflexes are lightening fast, enabling him to evade punches and counter with pinpoint single shots. Pacquiao's strength lies in throwing rapid combinations in short, sharp bursts at a pace he is able to sustain over 12 rounds.
Pacquiao has not stopped an opponent since toppling Miguel Cotto in 2009, but the eight-weight champion is the bigger hitter with the straight southpaw left his most concussive shot. Discounting the sucker punch that dispatched Victor Ortiz, Mayweather's last early night came against Ricky Hatton eight years ago.
Another strength shared by both fighters that takes alternative forms. Mayweather glides around the ring with flawless footwork, using his clever placement to command space. While less slick, Pacquiao is able to dance in an out of range and attack from different angles.
Mayweather is a master tactician with the ability to adapt, using the opening rounds to work out his opponent. By the second half of the fight he is in full control and picks apart his foe with clinical efficiency. Since his knockout by Marquez, Pacquiao has proved more cautious but he will never outthink Mayweather.
Mayweather's defensive expertise means his chin is rarely tested, although when he has been caught he has shown his survival instincts, most notably in riding a big right hand from Shane Mosley five years ago. Pacquiao has been knocked out three times. Two of those were early in his career and can be discounted, but it is the sickening blow landed by Marquez that places his ongoing punch resistance under the microscope.
Bookmakers view Mayweather as 1/2 favourite - Pacquiao is widely available at 15/8 - and it is hard to look beyond the Las Vegas resident extending his flawless record to 48 victories. Pacquiao will apply relentless pressure, but Mayweather will pick the Filipino apart for a unanimous points victory.