By Ryan Burton

The Julio Cesar Chavez Jr-Sergio Martinez pay-per-view undercard is starting to take shape.  Last week BoxingScene first reported that a fight between WBA super bantamweight champion Guillermo Rigondeaux and prospect Robert Marroquin (22-1)  was being discussed for the September 15th card that takes place at the Thomas & Mack Center in Las Vegas, NV.

Marroquin has informed BoxingScene.com that he has signed his contract to face Rigondeaux (10-0) and confirmed that the fight will take place underneath the  Chavez Jr-Martinez grudge match.

Rigondeaux represents a huge step up in class for the once beaten Marroquin.  The 22-year old Dallas native plans on using his power and reach advantage to shock his Cuban opponent who is sure to be a heavy favorite.

"This is a huge opportunity that I need to take advantage of," stated Marroquin.  "Rigondeaux is the best super bantamweight in the world but this is boxing, one punch can change an entire fight.  I feel strong at 122 and need to take advantage of my height and reach."

Marroquin bounced back from the only blemish on his record, a split decision loss to Francisco Leal in April 2011 by reeling off three wins in a row.  He said that his trainer has gotten him back to doing the things that made him one of the most promising prospects in the lower weight divisions.

"Paul Reyes has taken me back to the basics and I know that relying on my jab and simple one-two combinations can get me the victory," Marroquin told BoxingScene.com.  "It's time to hit the gym and get ready because this will be the toughest match of my life."

Send questions or comments to ringsidewriter@gmail.com Follow Ryan on Twitter @ringsidewriter and tune in to The Boxing Lab, BoxingScene's official audio on Tuesdays. The show is hosted by Ernie Gabion, Luis Sandoval and Ryan Burton