Watch Mayweather vs Guerrero online live stream fight details, results and start time for Showtime PPV TONIGHT!

"May Day" has finally arrived.

Boxing is back on tonight (May 4, 20123) with its biggest box office draw, Floyd Mayweather Jr., who returns from a year-long absence, which included a stint in prison for domestic abuse, putting his WBC Welterweight championship -- and perfect professional record (43-0) -- on the line against 147-pound WBC interim champion Robert Guerrero on the line at MGM Grand Garden Arena in Las Vegas, Nevada.

"Mayweather vs. Guerrero" starts at roughly 9 p.m. ET with a live stream of the under card bouts, including Daniel Ponce De Leon vs. Abner Mares, J'Leon Love vs. Gabriel Rosado and Leo Santa Cruz vs. Alexander Munoz, that will air on Showtime pay-per-view (PPV).

MMAmania will have LIVE results, coverage and updates of "Mayweather vs. Guerrero" all night, starting with the Showtime broadcast at 9 p.m. ET RIGHT HERE.

To watch the pay-per-view (PPV), which, of course, features the big Floyd Mayweather Jr. vs. Robert Guerrero prize fight in the main event, as well as three other magnificent match ups, including Daniel Ponce De Leon vs. Abner Mares, you can call up Comcast or your local cable and/or satellite provider (DirecTV, DISH Network, etc.) and order the show on your television. There is also a helpful and comprehensive list of cable providers featured on inDemand.com for your convenience.

If you would rather take in the show at your local watering hole, click here to find out where the bar closest to you is broadcasting the event.

International viewing options include, but are not limited to:

BoxNation (UK)

However, if you need your Mayweather vs. Guerrero results as soon as possible, for free, MMAmania.com will deliver up-to-the-minute results and live fight coverage, including round-by-round, blow-by-blow coverage of all the Mayweather vs. Guerrero action before, during and after the event RIGHT HERE.

More details on the Mayweather vs. Guerrero main card, who is fighting who, as well as how to keep yourself updated all night long, below:

147 lbs.: Floyd Mayweather vs. Robert Guerrero
126 lbs.: Daniel Ponce de Leon vs. Abner Mares
160 lbs.: J'Leon Love vs. Gabriel Rosado
122 lbs.: Leo Santa Cruz vs. Alexander Munoz

Remember, too, that our under card quick results will begin to flow around 7 p.m. ET later this evening and run right on through to our main card PPV coverage, which is set to start at 9 p.m. ET, from the MGM Grand Garden Arena in Las Vegas, Nevada. Expect Mayweather and Guerrero to enter the squared circle around midnight.

To get up to speed on all the news and notes for Mayweather vs. Guerrero be sure to hit up our comprehensive event archive right here.