Jonathan Horton woke up Monday with a feeling that a gold medal could be at hand for the U.S. men’s gymnastics team.

After all, the Americans had trounced China, the defending Olympic champions, in Saturday’s qualifying to establish themselves as favorites for the coveted team gold medal at these London Olympics.

As the U.S. team’s captain and chief cheerleader, Horton, 26, pulled his fellow gymnasts together to share his gilded vision, telling them shortly before the team final that they could return to the Olympic Village that night as Olympic champions.

After a disastrous performance relegated the Americans to fifth, their worst showing since finishing fifth at the 2000 Sydney Games, Horton was left to wonder if he hadn’t pushed the wrong emotional buttons in his pre-competition pep talk.

“Maybe that was a little bit of my fault,” said Horton, the lone holdover from the U.S. team that won bronze at the 2008 Beijing Games. “Maybe I should have kept everyone a little more relaxed.”

As the U.S imploded at North Greenwich Arena, China crushed all comers, defending its 2008 gold with performances that were technically rigorous and soundly executed across the board to finish with 275.997 points. No other country got within four points of that mark.

Japan (271.952) took silver, successfully appealing a pommel-horse score to deny Britain second-place honors. The host nation settled for bronze — an achievement that British fans met with wild enthusiasm, nonetheless, given that their men’s gymnasts hadn’t won an Olympic team medal since 1912.

The Americans’ fifth-place finish represented a stunning fall for a team many felt would make history Sunday. No U.S. men’s squad had ever won gymnastics’ prestigious team gold in a non-boycotted Games. The Americans took top honors at the 1984 Los Angeles Olympics, but Russia, then a gymnastics power, didn’t take part.

Whatever self-recrimination Horton felt in the aftermath Sunday was entirely misplaced. The Americans’ collapse was total, with every gymnast (save Horton himself) underperforming to breathtaking degree.

The team’s two best gymnasts, Danell Leyva and John Orozco, who qualified for the individual all-around competition, had particularly bad days.

Orozco lost his composure entirely and “sat” on the pommel horse, incurring a costly deduction on a routine in which only the hands are allowed to contact the apparatus. His score, 12.733, was 23rd among all 24 competitors. Then he fell on the landing of his vault. And Leyva flew off the pommel horse midway through his routine, earning a sub-par 13.400.

“It just didn’t go as planned,” said Orozco, 19, of the Bronx, who posted the lowest score for the Americans on four of the five events in which he competed.

Midway through the competition, after three of the six mandatory events were complete, the U.S. men were dead last among the eight nations vying for the team crown, out-performed by such non-gymnastic powers as France, Germany and the determined host nation.

They rallied down the stretch, finishing with strong overall performances on the parallel bars and high bar, events in which none of the three Americans fell and all scored 15 points or higher.

But with Britain performing brilliantly on its last rotation, the floor, the American rally was too little and too late, lifting them to fifth. As Orozco and Leyva buried their heads under towels, officials sorted out the scoring controversy that shuffled positions two through four, vaulting Japan ahead of Britain and knocking Ukraine, which initially was credited with bronze, out of the medals entirely.

In Olympic team finals, each country fields three athletes in six mandatory events: the floor, pommel horse, rings, vault, parallel bars and high bar. Because all three gymnasts’ scores count, a country is best served by having three technically and mentally sound performers on each apparatus rather than a few high-strung stars. That should have served the U.S. men well, based on their solid showing in qualifying. But Monday, only Horton and Jake Dalton, who competed in the fewest events, avoided costly errors.

In the interviews that followed, none of the U.S. gymnasts said they had been nervous or felt paralyzed by the pressure and the stage. With only slight variation, they chalked up their poor performance to an “off day,” as if the outcome could have been different on another day.

“I don’t think we were all super-nervous or anything like that,” said Leyva, 20, of Miami. “I honestly think we all had somewhat of an off day. It wasn’t our day today. It’s all right. We’re going to use this as fuel for the next time.”

The pity is, Olympic finals come but once every four years — a fact that seemed to elude this young U.S. team. And there’s no certainty that any one of them will qualify for Brazil in 2016.

No Olympic athlete wants to leave the Games without a medal, but it’s a disappointment most manage to bear as long as they know they performed their best. What’s unbearable, veteran athletes say, is to leave an Olympics knowing that you failed to do your best. And that’s the burden some of these American gymnasts will bear for another four years, assuming they’re fortunate enough to return in 2016, or longer, if this is their finale.

“Right now, it’s over,” Orozco said. “I don’t feel fantastic about it. All I can do is look forward to the future.”