By Dan Ambrose: WBA/WBO lightweight champion Juan Manuel Marquez (50-5-1, 37 KO’s) has a lot to gain by beating Juan Diaz (35-3, 17 KO’s) in their rematch on July 31st at the Mandalay Bay Resort & Casino, in Las Vegas, Nevada. The rematch in itself is no longer really important, as both fighters have been soundly beaten since their fight last year and much of the boxing public has totally forgotten about their original fight way back in February 2009.

However, it will be a somewhat interesting fight to see how much Marquez has left against a younger fighter that has lost three out of his last five fights. But the real interest is what comes after this for Marquez if he beat Diaz once again. Marquez has a number of options available to him for his next fights. Should he choose to stay at lightweight, Marquez could take on the WBO lightweight interim champion Michael Katsidis in what would be almost certainly be a thrilling fight from start to finish.

Katsidis, who previously was beaten by Joel Casamayor and Diaz in the past couple of years, has resurrected his career and has beaten two top lightweights Vicente Escobedo and Kevin Mitchell in his last two fights. A fight between Katsidis and Marquez would be huge and very competitive while it lasts.

Marquez also can fight the winner of the Humberto Soto vs. Marco Antonio Barrera fight. It’s likely going to be Soto that emerges the winner of Soto-Barrera fight, but it would still be a great fight for Marquez. It might be a little less interesting if Barrera comes out the winner, because Marquez already beat Barrera three years ago by a lopsided 12 round decision. A fight against the Barrera vs. Soto winner isn’t nearly as huge as some of the other fights out there for Marquez.

WBA light welterweight champion Amir Khan badly wants to fight the winner of the Marquez-Diaz fight, and especially wants to fight Marquez. However, it will require for Marquez to move up in weight and take on Khan at 140 rather than Khan coming down to his weight class for the fight. It would be a trade off for Marquez. He would be putting himself at a huge disadvantage by having to gain weight to fight Khan, but Marquez would be well paid for having done so whether he wins or loses the fight. Marquez looked horrible in fighting Floyd Mayweather at a welterweight catch weight of 144. It would be very likely that Marquez, whose best weight was featherweight, would be slow and too heavy to do much against the bigger and faster Khan.

There’s an outside chance that Manny Pacquiao might opt to fight Marquez for a third fight between them. This is probably not very likely, though, because Marquez fights for a different promoter and Pacquiao’s promoter Bob Arum might prefer to keep matching Pacquiao up against his own fighters rather than putting him in with Marquez again. Pacquiao hasn’t looked good in his past two fights with Marquez, but he would likely be in a much better position in a third fight between them because it would likely have to take place at welterweight or near the welterweight limit. In other words, there probably be a catch weight for Marquez in this fight.