By William Mackay: With so few stars to fight in the lightweight division, the winner of the July 31st bout between WBA/WBO lightweight champion Juan Manuel Marquez (50-5-1, 37 KO’s) and Juan Diaz (35-3, 17 KO’s) will get the good luck of facing WBA light welterweight champion Amir Khan (23-1, 17 KO’s), who is waiting in the wings licking his chops at the prospects of fighting one of these smaller lightweights.

What this means is a good payday for the winner of the fight when get the chance to move up in weight to fight the 23-year-old Khan on HBO.

Sure, Khan doesn’t have the same qualifications or the same experience as Diaz and Marquez, but he’s well liked by HBO, and is being pushed by Golden Boy Promotions in hopes of making Khan a mega-star along the same lines as Floyd Mayweather Jr. and Manny Pacquiao.

Marquez and Diaz fought last year in one of the most exciting fights in all of 2009. Diaz was competitive in the early rounds, but unable to handle the uppercuts from Marquez. Diaz ended up getting chopped down in the 9th round.

Besides the uppercuts, which Diaz had no clue how to stop, he was also dealing with a nasty cut that obscured his vision and made it even harder to deal with Marquez’s hard punches.

Diaz has been working on how to defend against Marquez’s uppercuts in training. However, Marquez is a fighter that takes advantages of your mistakes, so he’s going to find something to take advantage of in the fight no matter how hard Diaz prepares for the bout.

Marquez was easily beaten by Floyd Mayweather Jr. last year in a one-sided 12 round deicison in September. One questions that lingers from that loss is how much Marquez has left in the tank. He looked slow and lethargic in that fight and wasn’t even slightly competitive.

It could be that Mayweather was just too good for Marquez to handle, but it also could be a case of Marquez starting to show his age and beginning to slip. He’s 36-years-old now, and about to turn 37. That’s old for a smaller fighter like Marquez.

He’s facing a much younger fighter in 26-year-old Diaz, and if the younger fighter has fixed the mistakes he made in his last fight, he could have too much youth and energy for the aging Marquez to handle. Sometimes a fighter like Marquez can get old overnight. Will we see that With Marquez on July 31st. It’s possible.