The possible descent of one of the sport’s best fighters and emergence of new faces into relevance underscored boxing in 2012. Transition appears imminent based on the year’s noteworthy events.

The sport’s mountaintop no longer features Manny Pacquiao. Exchanging turns with Floyd Mayweather Jr., at pound-for-pound elite the past four years, Pacquiao suffered two losses within a six-month period.

Pacquiao’s first setback against Timothy Bradley in June was highly disputed considering that Pacquiao controlled the pace most of the bout but lost a controversial split decision. But the Philippines native’s second loss six months later sent shock waves.

Mexico’s Juan Manuel Marquez finally defeated Pacquiao after three previous unsuccessful attempts. Marquez knocked Pacquiao out cold in the sixth round of their welterweight fight. The sight of an unresponsive Pacquiao lying on the canvas for a few seconds was a far contrast from the fighter who overwhelmed foes through six weight classes.

With Pacquiao looking so fallen, the always-talked-about but never-materialized fight between Pacquiao and Mayweather has lost substantial impact. Mayweather, whose only bout of the year was a decision win over Miguel Cotto in May, and Pacquiao never agreed to the potential blockbuster match.

Mayweather made news outside the ring. Soon after his victory over Cotto, Mayweather served a two-month prison sentence for domestic battery.

Like Pacquiao, Cotto lost in his two ring appearances this year. Cotto’s loss against Mayweather ended his stint as junior-middleweight champion. In December, Cotto attempted to recapture another junior-middleweight belt, but lost a decision against Austin Trout.

Argentina’s Sergio Martinez won a middleweight title and capitalized on his first pay-per-view opportunity with a convincing decision over Mexico’s Julio Cesar Chavez Jr., in September. Martinez dominated the first 11 rounds, but survived a 12th-round knockdown and dramatic late comeback from the previously unbeaten Chavez.

A typical knock from boxing critics is how the sport won’t overcome the departure of its crossover stars. When an aging Oscar De La Hoya lost his final bout against Pacquiao four years ago, skeptics said boxing was left without pay-per-view performers only to have Pacquiao and Mayweather take over.

In 2012, boxing had a new group of fighters that could eventually headline pay-per-view dates. Already among the sport’s best fighters, super-middleweight champion Andre Ward solidified his status with a 10th-round technical knockout win against light-heavyweight titleholder Chad Dawson in September.

Philippines’ native Nonito Donaire is becoming one of the best fighters in the smaller weight classes. Donaire remained busy during the year with four successful defenses of his 122-pound title.

Another fighter making an impact in the lower weight divisions is Adrien Broner. The 23-year-old native of Cincinnati made two successful defenses of his junior-lightweight belt, then moved up to the lightweight class and captured his second weight-division title with an eighth-round TKO over Antonio De Marco in November.

Junior-welterweight Danny Garcia, 24, is another fresh face on the verge of stardom. In March, Garcia, of Philadelphia, won a 140-pound world title with a decision against future Hall of Famer Erik Morales. Three months later, Garcia scored a fourth-round TKO over Amir Khan. Garcia concluded his successful year with a fourth-round knockout win over Morales in October.