LONDON (AP) -- While Joseph Diaz Jr. dominated from the first punch of the Olympic boxing tournament, teammate Terrell Gausha waited until the final seconds for an incredible stoppage victory.
Although the Americans went about it in dramatically different ways, they got the games off to a rousing start for a former amateur boxing power looking to get back on top.
Diaz looked sharp in a 19-9 victory over Ukraine bantamweight Pavlo Ishchenko in the tournament's opening bout Saturday, while Gausha knocked down Armenian middleweight Andranik Hakobyan twice in the final 7 seconds of his middleweight bout, winning by stoppage with no time on the clock.
"However you have to get it done, we're going to do it," Gausha said. "I knew I had to leave it all in the ring."
Gausha's dramatic finish was the most exciting bout of the opening day at ExCeL.
After three fairly even rounds, Gausha abruptly put Hakobyan on his back on the canvas twice in the final seconds. The Cleveland product first followed his jab with a big overhand right for a knockdown that clearly discombobulated Hakobyan, who didn't appear prepared when the referee resumed the bout.
Although the clock was all zeros, the bell hadn't rung - and Gausha knocked down Hakobyan again. The referee stopped the fight before the count, and Gausha celebrated his win by waving to his mother and sister, whose trip from Cleveland was sponsored by friends and fans.
"My coaches told me to pick it up and just let my punches go," said Gausha, who acknowledged he wasn't aware of the lateness of his finish. "I kind of have a mental clock in my head, and I knew I was cutting it close."
British middleweight Anthony Ogogo won the hosts' first bout, beating the Dominican Republic's Junior Castillo 13-6 to thrill a raucous crowd. Ireland's John Joe Nevin and Darren O'Neill also rode the crowd's cheers to opening-round victories, and Diaz became a crowd favorite after the Los Angeles-area native put on a rousing display of speed and power.
While most of Diaz's American teammates walked in the opening ceremony, he stayed in his room and studied his first Olympic opponent on YouTube. Diaz then put on a performance that could have fight fans worldwide searching for his highlights very soon.
Diaz relied on his scouting and ample talent to blast Ishchenko, repeatedly catching his opponent in the later minutes with those unblocked, head-moving punches that consistently count for points in amateur boxing. An elite pro prospect, Diaz repeatedly snapped back Ishchenko's head with uppercuts and quick strikes during a dominant third round, delighting the 19-year-old's father and family in the stands.
"I just feel the momentum, the extra boost they're giving me," Diaz said. "I just step in and give him my extra strength and my extra conditioning. My family is everything, and I'm trying to bring back a medal for them. ... I felt like (Ishchenko) got a little tired, and I felt like I was just getting started."
Diaz earned a second-round bout Wednesday with Cuba's Lazaro Alvarez, the tournament's top-seeded boxer - but he also captured the attention of promoters, managers and an entire bantamweight division that's probably grateful Diaz and Alvarez must fight each other early.
"I had a really tough draw, and I know the Cuban is the No. 1 seed, but I'm confident," Diaz said. "I think I'm giving the whole Team USA a boost. Everybody will be even more motivated."
The American fighters in the stands cheered wildly for their teammates, reflecting the much-improved camaraderie on a team that squabbled and underachieved its way to just one bronze medal in Beijing. U.S. boxers have won far more medals than any other nation in Olympic history, leading second-place Cuba 108-63 heading into London, but have won just seven medals in the last three Olympics - and just one gold, by Andre Ward in 2004.
"When one of us wins, we all win," Diaz said.
Ogogo already is a popular fighter at home, where he stars in commercials. After his solid victory, the British middleweight revealed his mother went into the hospital six weeks ago after a brain hemorrhage left her in a coma.
Ogogo says his mother is doing "really well" - and she's just down the hall at the hospital from her oldest daughter, who went into labor with her second child shortly before Ogogo's bout. Ogogo's other sisters attended his fight.
"Hopefully I'll get out of here and find out I have a niece or nephew," he said.
Former Russian world champion Sergey Vodopyanov also won his opening bout. Vijender Singh, the middleweight who won India's first boxing medal in Beijing, won a 14-10 decision over Kazakhstan's Danabek Suzhanov.
Georgian middleweight Merab Turkadze forfeited his evening bout after failing to make weight, allowing Algeria's Amine Mohammed Ouadahi to win by walkover.
Syria's only Olympic boxer, bantamweight Wessam Slamana, lost his opening bout to Kazakhstan's Kanat Abultalipov. Slamana trained mostly in Kazakhstan, Mongolia and Wales in recent months, but also spent 10 days working out in Damascus.