By Ryan Maquiñana

Floyd Mayweather Jr. has finalized a deal to fight Robert Guerrero on May 4 at the Las Vegas MGM Grand, sources with knowledge of the negotiations informed CSNBayArea.com/BoxingScene.com Tuesday morning.

In a bit of an upset, Showtime will broadcast the pay-per-view event, edging archrival HBO for the rights.

Guerrero (31-1-1, 18 KOs), currently the WBC interim welterweight titleholder, will take on the full-fledged WBC champion Mayweather (43-0, 26 KOs) for the belt.

Unbeaten junior middleweight titleholders Saul “Canelo” Alvarez (41-0, 30 KOs) of Mexico and Austin Trout (26-0, 14 KOs) of Las Cruces, N.M. will unify their belts in the co-feature.

Ryan Maquiñana was the boxing producer for NBCOlympics.com during London 2012 and writes a weekly column for CSNBayArea.com.  He is a full member of the Boxing Writers Association of America and the Ratings Panel for Ring Magazine. E-mail him at rmaquinana@gmail.com , check out his blog at Norcalboxing.net, or follow him on Twitter: @RMaq28.