LAS VEGAS -- Floyd Mayweather Jr., who ranks No. 1 in SI.com's pound-for-pound ratings and was back in action for the first time since outpointing Miguel Cotto on May 5, 2012, improved his record to 44-0 and defended his welterweight title against former featherweight, junior lightweight and interim lightweight champion Robert Guerrero (31-1-1, 18 KOs). Bryan Armen Graham live blogged all the action from ringside at the MGM Grand Garden Arena in Las Vegas.
ROUND 1: Feeling out early in the center of the ring. Guerrero looks dry. The fighters get tied up and Guerrero holds and hits Mayweather, but Floyd looks prepared for it. More holding and hitting from Guerrero in the opening 90 seconds. Mayweather tries to land a right-hand lead but Guerrero deflects it. Mayweather moving well. Tense moments early. Guerrero catches Mayweather lunging inside with a hard right hand and managed to wobble Floyd slightly. A good competitive round. Guerrero knows Floyd will throw lots of rights and looks like he's trying to time them. Guerrero 10-9.
ROUND 2: Mayweather lands a straight right, but Guerrero fires back with a combination. Guerrero trying to pressure and crowd Mayweather, but Floyd able to get out of trouble with deft footwork and good use of the jab. Looks like Floyd is the one initiating clinches. Guerrero is making this a rough fight. Two very close rounds that could have gone either way, but right now I have Guerrero ahead 20-18. Guerrero 10-9.
ROUND 3: Guerrero said yesterday he wasn't intimidated and clearly he's not, but Mayweather lands flush with a right-hand lead to start the third. Floyd now making Guerrero miss those counters. Mayweather is connecting with that right-hand lead with greater frequency. Looks like Mayweather was just warming up: a clear-cut Floyd round. Mayweather 10-9.
ROUND 4: Guerrero needs to figure out a way to stop getting hit by those rights. Another there really moved him back and whipped the crowd into a frenzy. Incredible precision from Floyd, who is landing more and more. Another very hard right from Mayweather, who's really working here and making Guerrero look tentative. Floyd is allowing Guerrero to back him down into corners then either making flight or delivering hard shots to the body. Mayweather, easily again. Mayweather 10-9.
ROUND 5: Mayweather circling the ring. Guerrero throws a combination to Floyd's abdomen but Mayweather holds. Nice right hand from Guerrero there. Mayweather is picking Guerrero apart now, using the challenger's aggression against him like he's done to so many other opponents through the years. It was closer than rounds three and four, but you've got to give it to Floyd. Mayweather 10-9.
ROUND 6: Guerrero chasing Floyd around the ring. Mayweather starting to open up here, perhaps sensing the challenger's fatigue. A straight right from Mayweather snaps back Guerrero's neck. There's another straight right from Floyd, who is landing that punch with alarming ease. This is a clinic. Mayweather 10-9.
ROUND 7: A look of worry on Guerrero's face as the second half of the fight gets underway. Mayweather slipping shots, scoring with the right at will. Guerrero misses badly with with left hook. The challenger seems to be using his head a little more now, starting to make it dirty. Easy money for Floyd. Mayweather 10-9.
ROUND 8: More flawless technique from Floyd. A masterclass in ring generalship. Another stright right from Mayweather. (Sound familiar?) Guerrero bleeding now, cut over left eye from a punch. The only question that remains is whether Guerrero, who appears broken mentally, will make it to the final bell. A massive right hook from Mayweather -- the biggest punch of the fight so far -- set up by a left jab. This was a huge round for Floyd, who landed a staggering 23 of 30 power shots per CompuBox. The end is near. Mayweather 10-9.
ROUND 9: More of the same from Mayweather. A fierce beatdown from the champion. Lather, rinse, repeat. Mayweather 10-9.
ROUND 10: Still no answers for Guerrero, who is eating a steady diet of rights and now lefts from the master. An absolute blowout. Crowd getting a little restless. Scattered boos. Mayweather 10-9.
ROUND 11: Mayweather continues to whip hooks at Guerrero's head. Mayweather winks at Guerrero's corner when they're tied up. Floyd just needs to stay on his feet to win the fight. Mayweather 10-9.
ROUND 12: Kind of an anticlimactic finish here as Mayweather plays out the string. Boos from the crowd throughout the frame with some fans even heading for the exits but Mayweather does more than enough to take it. I have him winning 118-110, which may be a charitable score for Guerrero: this could easily have been a shutout. Mayweather 10-9.