RIO DE JANEIRO -- Jose Aldo stopped Chad Mendes with one devastating knee to the head with a second left in the first round Saturday night, defending his featherweight title in his homeland at UFC 142.
Aldo (21-1) spun and knocked the previously unbeaten Mendes senseless on his back with a perfectly timed right knee that caught Mendes (11-1) flush in the face.
Aldo then landed two punches to Mendes' defenseless head before referee Mario Yamasaki stopped the bout before the bell.
Aldo then bolted from the octagon and sprinted into the HSBC Arena crowd, which raised him on its shoulders to cap the UFC's second event in Brazil in six months after a 13-year absence.
Aldo has won 14 straight fights since November 2005, including three defenses of the UFC's first featherweight title belt.
"This is why I do this," Aldo said through a translator. "I'm so happy to be fighting at home."
The card featured several dramatic finishes by Brazilian fighters for the sellout crowd. Former UFC champion Vitor Belfort stopped Anthony Johnson with a first-round submission, and Rousimar Palhares beat Mike Massenzio with a first-round leglock.
In the main event, Mendes repeatedly tried to take down Aldo, hoping to showcase the Sacramento-based fighter's impressive wrestling abilities. But Aldo has perhaps the UFC's best takedown defense, and he parried every attempt until Mendes managed to get behind Aldo late in the round.
Mendes pinned Aldo against the cage for more than a minute, but Aldo spun out of Mendes' grip and floored the American fighter, who ducked his head right into Aldo's knee.
"I felt the best I've ever felt for a fight," Mendes said. "I was very prepared, and he just got me. Watching a lot of his fights I knew it was going to be tough to take him down. He's very athletic."
Johnson (10-4) was an astonishing 11 pounds over the middleweight limit Friday, forcing the UFC to fine him 20 percent of his purse. Belfort agreed to move the bout to a 197-pound catch weight.
Johnson was unlikely to have much stamina after attempting to cut weight, and Belfort won after weathering a furious start in which Johnson closed Belfort's right eye. The Rio de Janeiro eventually got on top of Johnson and choked out the American contender, who had lost just once in his last six fights.
"I'm back on track," said Belfort, the former UFC light heavyweight champion. "I'm focused on my goal, and I'll pursue it."
Belfort's only loss since October 2006 was a first-round knockout on a kick from Anderson Silva in a bout for the UFC middleweight title last February.
Palhares (23-3) added to his fearsome reputation for impressive ground skills with a gruesome heel hook on Massenzio (13-6), who tapped out in agony to end their middleweight bout at 1:20 of the first round. Palhares has won six of his last seven fights.
Barboza (10-0) delivered what's certain to be one of the year's most impressive knockouts at 2:02 of the third round of his lightweight fight. Etim was out on his feet when the heel kick landed.