LONDON (AP) -- The U.S. men's boxing team is heading home with no Olympic medals for the first time.
Spence represented the last chance for the most successful team in Olympic boxing history to add to its record 108 medals. Instead, the Dallas-area fighter started slowly and never got going in his team's ninth loss in 10 fights.
Given a second chance to avoid the shutout, Spence felt he had no reason to argue this loss.
"I'm glad a better guy beat me this time, because I didn't like the way I went out last time," Spence said. "I didn't think about the pressure on the team. I just tried to fight my fight, and it didn't work out. He was the better man."
Spence struggled to feel out Zamkovoy, a more polished amateur boxer who knows how to hit and get away. Spence marginally upped his aggression in the third round, but couldn't land nearly enough scoring blows.
The Americans won their first four fights on the opening weekend in London, but never again left the ring with their arms raised. The U.S. men did even more poorly than the squabbling, backbiting Beijing team that had the previous worst performance - yet at least that team won six fights and Deontay Wilder's bronze medal.
U.S. women's boxers Marlen Esparza and Claressa Shields already have clinched medals in their sport's debut tournament, but the team that sent giants from Cassius Clay to Oscar De La Hoya on to Olympic success is at its nadir.
"I think the foundation is kind of crumbling a little bit, but we're going to rebuild it," U.S. assistant coach Charles Leverette said. "The support is there, but we have to figure out the best way to help these athletes get back to the top."
Aside from the American team's quiet exit, the card at ExCel arena featured solid action and eight more fighters clinching medals.
Two more fighters protested the results of their bouts after losing on countback tiebreakers in an increasingly bad-tempered tournament. Amateur boxing's governing body was expected to rule on the protests late Tuesday night.
France's Alexis Vastine put on a theatrical display of disappointment after losing to top-seeded welterweight Taras Shelestyuk of Ukraine, flopping on his back in the ring and punching a turnbuckle before collapsing in the tunnel in body-shaking sobs.
Canada also protested Clayton's loss to Evans, which denied Canada its first boxing medal since 1996 for the third time in these Olympics.
The session also included two of the most impressive fighters in the London Olympics.
Top-seeded flyweight Misha Aloian of Russia continued his outstanding tournament by reaching the semifinals with a 23-13 win over Puerto Rico's Jeyvier Cintron, and Cuba's Robeisy Ramirez pulled off one of the most difficult feats at these Olympics when he beat a British boxer, flyweight Andrew Selby.
Selby fought gamely, but couldn't keep up with the talented Ramirez, who broke through his defeat repeatedly to score points. Selby was the second-seeded flyweight after winning a silver medal at last year's world championships, but said he's open to staying in the amateur ranks until Rio.
"He wasn't so much fast, he was just clever," Selby said. "He knew when to hit me at the right time, and he's very strong."
Vastine was a bronze medalist in Beijing, but he left the Olympics feeling robbed for the second straight year after dropping a decision to gold medalist Manuel Felix Diaz of the Dominican Republic in 2008 on a final-round point deduction.
Vastine felt he had decisively won a close fight with Shelestyuk, who won on countback. Vastine then put on a show of disappointment to the whistling crowd, sitting and then lying on the canvas in tears before getting up and punching the cushion on the ropes.
When he finally made it to the tunnel, he gave a hysterical interview to a television reporter before collapsing in sobs - and hurling a large water bottle so hard it broke on the floor.
Clayton took his narrow loss with much more aplomb, praising Evans while acknowledging the home crowd is an obstacle just as large as the fighter.
"I didn't even hear them against me, but it probably makes a difference sometimes on the scorecards," Clayton said. "It felt like a close fight, but I thought I won."
Aloian was roundly impressive in dispatching Cintron and his imaginative mullet haircut. Aloian's next fight should be a corker against Mongolia's Tugstsogt Nyambayar, another entertaining brawler who clinched a medal by beating Uzbekistan's Jasurbek Latipov.