Aldo looked comfortable for most of the championship contest, standing firm in the pocket and offering stiff counter shots each time Jung moved forward with flurries of kicks and punches. A few takedowns late in the opening round earned Aldo additional points, and he was up big on the judges' cards heading into the championship rounds.
The champion did seem to slow as the bout wore on, taking a few deep breaths and stalling out in a few wrestling positions against the cage. But just as Jung turned up the heat to try to capitalize, his right shoulder dislocated during an errant punch, leaving the challenger vulnerable.
Aldo sensed the opening and unleashed a series of high kicks that crashed into the arm and sent Jung to the ground. Aldo immediately pounced with more punches from the top, and referee Herb Dean waved off the fight at the 2:00 mark of the fourth round.
Jung immediately turned over and grabbed his shoulder, grimacing through the pain.
"I did see that he separated his shoulder, so I kicked him and tried to put him down on the ground to give him some ground and pound," Aldo said.
As it turned out, Jung wasn't the only one who suffered an injury, as Aldo revealed at the post-event press conference that he had suffered a potentially broken foot on the first kick of the fight.
With the victory, Aldo is now riding a 16-fight win streak and remains the lone featherweight champion in UFC history. Jung sees a three-fight win streak snapped and falls short in a bid to become the first Asian-based champion in UFC history.
In the night's co-feature, Phil Davis (12-1) earned a unanimous-decision nod against former UFC champion Lyoto Machida (19-4) in a hard-fought three-round affair.
A vaunted wrestler, Davis struggled to get the action to the floor until very late in both the second and third rounds. Davis stayed busy on his feet, kicking the legs and body while doing his best to avoid Machida's counterpunches. Meanwhile, Machida looked very comfortable on his feet but never really overwhelmed Davis with his striking, leaving all three of the rounds relatively closely contested.
In the end, judges gave Davis the unanimous-decision nod, 29-28 on all three cards, in a result that proved wildly unpopular with the Brazilian crowd.
"I've been a fan of Lyoto Machida since I started in the UFC. This man is awesome," Davis said as the crowd booed. "The late takedowns definitely helped. It's just part of what I do."
In middleweight action, "The Ultimate Fighter: Brazil" winner Cezar Ferreira kept his UFC record perfect with a 47-second submission win over first-time UFC fighter Thiago Santos. Ferreira landed an early left hand that wobbled his opponent, and he followed with a quick high kick.
With Santos hurt, Ferreira jumped forward, locked in an arm-in guillotine choke and rolled until he could get a firm squeeze. Trapped in the choke, Santos had no choice but to tap. The whole process took just 47 seconds.
Fighting in the UFC for the first time nearly four years, Rio de Janeiro native Thales Leites (21-4) earned an impressive unanimous-decision win over British slugger Tom Watson (16-6). Leites outgrappled Watson throughout the 15-minute affair, repeatedly bringing the action to the floor and keeping his opponent out of his comfort zone.
Watson showed great heart by battling through a handful of impressive submission attempts, but Leites was awarded the unanimous-decision win.
"I tried submitting him; unfortunately I didn't," Leites said. "He did a great job blocking me in the first round and came back stronger for the second, but I was ready."
In the night's card-opening contest, flyweight contender John Lineker (22-6) earned his third-straight win with a second-round TKO over promotional newcomer Jose Maria (33-4). Despite the impressive performance, Lineker's chances of receiving a title shot for the victory seem slim after failing to make weight for the second time in four UFC appearances.
"I must say it's always a bit upsetting facing a fellow Brazilian," Lineker said. "He also went through a lot in his life, and taking this away from a countryman is a bit sad."
UFC executive Marshall Zelaznik reported an attendance of 13,873.