This is the matchup they've been waiting to see: Four belts, two undefeated fan favorites and a title fight simply billed as "The One."
"Canelo, I appreciate you for taking the fight," Mayweather said on a steamy Monday in the heart of Manhattan in front of a few thousand fans standing behind metal barriers or sitting in temporary bleachers with Broadway marquees serving as a colorful backdrop.
"Now," Mayweather said, "let's give the fans what they want to see."
The fighters kicked off an 11-city tour to officially announce and promote their title fight at the MGM Grand in Las Vegas on Sept. 14. The promotional tour includes stops in cities such as Washington D.C., Chicago, Miami and Mexico City, and is jumpstarting the hype ahead of one of boxing's most anticipated bouts in recent memory.
Mayweather, 36, is unbeaten in 44 fights with the last a unanimous 12-round decision over Robert Guerrero on May 4 in defense of his 147-pound title.
"The Earth is my turf," Mayweather said. "You can put me in any ring and I will always come out victorious."
Alvarez, a 22-year-old star from Mexico, is 42-0-1 and unified the 154-pound titles in April with a unanimous victory over Austin Trout on April 20.
"In the sport of boxing, it's everybody's time, and this is my time," Alvarez said through a translator as fans chanted "Mex-i-co!"
"I'm going to win."
The 12-round fight will be contested at 152 pounds with both men's super welterweight/junior middleweight titles on the line Mayweather's WBA super welterweight "super" championship, and Alvarez's WBC, WBA and Ring Magazine super welterweight championships.
The bout, expected to be a monstrous draw on pay-per-view for Showtime, also just might satisfy many fans who had been wishing during the last several years for Mayweather to take on Manny Pacquiao.
"In every sport, there are certain rare occasions when you have the best fighting the best," said Stephen Espinoza, executive vice president and general manager of Showtime Sports. "The Super Bowl, Final Four, the college football national championship. Sept. 14 will be one of those occasions the two biggest stars in the sport, the two biggest fan bases.
"We have America's No. 1 fighter versus Mexico's No. 1 fighter. We have the No. 1 pound-for-pound fighter in the sport versus the No. 1 new star in the sport."
There remains some dispute over who set the 152-pound catch weight, with Mayweather's camp saying Alvarez's people brought it up first. Alvarez, however, insisted it was Mayweather who decided on having both fight at 152 pounds instead of 154.
"It wasn't me," Alvarez told reporters before the news conference. "I don't want to fight 2 pounds below my weight class."
There was also some contention between the two because Alvarez chose to headline his own fight card against Trout rather than be included on the undercard of Mayweather-Guerrero card. But both fighters agreed that this is a matchup that needed to happen.
"I've visualized this fight for years," Alvarez said, "and I feel I'm going to win."
The fighters each announced on Twitter last month that they would face each other, exciting boxing fans around the world. Monday's event marked perhaps the sport's most ambitious promotional tour since Mayweather and Oscar De La Hoya also stopped in 11 cities before their 2007 bout won by Mayweather. Alvarez has been picking De La Hoya's brain about fighting Mayweather, and the former champion believes the young star has a few advantages including youth he didn't have.
"I used reckless pressure and he's going to use smart pressure," De La Hoya said. "That's what going to be the difference. ... And I have three letters for (Alvarez): jab."
Each fighter took a stroll down a makeshift red carpet leading to the dais with pops of confetti marking their entrances. Mayweather received a noticeable amount of boos with the crowd appearing to slightly favor Alvarez.
One fan, though, got Mayweather to crack up when he held up a Chucky doll from the "Child's Play" movie franchise, taking a clear shot at Alvarez's hair color.
The two took their seats after their stare-down Mayweather next to Leonard Ellerbe, the CEO Mayweather Promotions, and Alvarez next to De la Hoya, the president of Golden Boy Promotions. It was a mostly tame news conference with the banter between sides at a minimum.
Before the news conference, Mayweather talked about shooting a commercial with the Spanish-speaking Alvarez and someone asked why he isn't doing his usual trash talking with his opponent.
"He wouldn't understand me anyway," Mayweather said, laughing.
It is the second in Mayweather's six-bout, 30-month contract with Showtime that could pay him more than $200 million. After Mayweather beat Guerrero, he said he wanted to fight again in September marking the first time since 2007 he will be in the ring twice in a calendar year.
"I said I was going to be very active so I could stay sharp and be at the top of my game," Mayweather said.
Mayweather showed little rust while dominating Guerrero by using superior defensive skills in his first ring appearance since serving a jail term for assaulting the mother of his children.
Alvarez is a confident and rapidly rising fighter who should provide a huge test for Mayweather. Alvarez was dominant against the previously unbeaten Trout, showing up some fans and media who speculated that perhaps he wasn't ready to face such an experienced opponent.
"To be the best," Alvarez said when asked before the news conference what his motivation is to fight Mayweather now. "(I want) to go down in history as the guy who beat the guy people consider the best."
When the news conference was over, both fighters got up and stared each other down one more time. And again, the crowd went wild.
"It's always been one of my ultimate goals to get to the pinnacle of the sport and push myself to the limit by facing the best," Mayweather said. "He's a young champion. What else can I say?"