BEIJING -- Reese Hoffa is a big, burly guy with an even bigger personality. That charisma faded into candid talk of failure when he missed medaling in the Olympic shot put and the Americans fell short of the gold-silver-bronze showing they had been confident they could attain.

"When everyone that you talk to is like, 'Hey, you're the guys who are going to sweep,' or, 'You're the Dream Team,' that kind of stuff, it kind of gets in your head a little bit," said Mr. Hoffa, of Athens, Ga.

"I try very, very hard not to listen to it, but it's going to be there. Just being an American thrower, there's always going to be that pressure."

For the United States, the Olympics carry a strong us-against-them theme, but it's one that has changed over the past several Games cycles.

The Americans no longer seem to have deep emotional rivalries with other nations as they did at the 1980 Winter Games in Lake Placid, N.Y., where the United States' upset of the powerful Soviet Union in hockey and subsequent gold-medal win against Finland seemed to transcend sports and unite the country.

The tension then between the United States and the Soviet bloc escalated and entwined with sports to the point that there were the Summer Games boycotts of the 1980s -- the Americans didn't go to Moscow in 1980 to protest the Soviet invasion of Afghanistan, so the Soviets didn't come to Los Angeles in 1984.

The Olympics since then has changed to allow professional athletes, leveling the playing field from a time U.S. entries were held to strict amateur standards while Soviet and Communist governments essentially skirted the rules.

At the 2008 Summer Games, the biggest rival for the United States is host China, but it seems to be based on sportsmanship and a desire to come away with the most medals and the most golds, not on the broader world issues that permeated the run-up to the Olympics, such as human rights, economics and the environment.

"I think the competition is great," said the Cleveland Cavaliers' LeBron James of U.S. men's basketball, the team most commonly called the Dream Team. "We're going to try to win as many golds as we can because you want to be the best."

The United States has won 72 medals, including 22 gold, ahead of China's total of 67 medals. However, the Chinese have won 39 gold.

The rivalries, then, stem from whichever athletes or nations present the toughest challenge.

"Every team is basically a rival here," U.S. baseball infielder Matt Brown, of the minor league Salt Lake Bees, said. "There's not one team out there that you want to beat more than another, as opposed to when I was in college and we wanted to beat Florida State or Miami."

China and the Americans are highly competitive in some sports, such as gymnastics, but there's little overlap in other sports. For example, the Chinese are not so well versed in sports such as softball and swimming, where the United States is competitive if not dominant. The Americans aren't a power in table tennis or badminton, which the Chinese do well.

Even in sports when both field strong medal hopefuls, there doesn't seem to be extra animosity. It's just about winning, not about beating an opponent from a particular nation.

"It's not from outside; it's definitely from within," said U.S. baseball pitcher Jeremy Cummings, who played for West Virginia University.

The Americans don't seem to be any sort of emotional target for athletes from other countries.

Ukranian Lyudmila Blonska had a strong 800-meter run to edge Pennsylvania's Hyleas Fountain for the silver medal in the women's heptathlon, but she got no added satisfaction from pushing a U.S. athlete down to bronze.

"My opponent is American, but it doesn't matter if she was American, French or British," Ms. Blonska said.

As for the Chinese, there is no outward indication their fans dislike the American athletes.

The Chinese seem to have gobbled up the majority of tickets to just about every event, and the fans are what you might call good sports, cheering everyone for good showings regardless of national affiliation -- except for their own athletes, who get booming roars.

It might be slightly different for the Chinese athletes and coaches, who could feel some pressure from sports and government authorities to win.

After his squad won the gold medal in the men's gymnastics team event, Chinese coach Huang Yubin said he wouldn't have to commit suicide as he had apparently joked about before.

The English-language China Daily newspaper sometimes takes mild shots at a perceived rivalry.

As the Chinese were advancing in badminton, a headline read, "One step closer to dominance." When Mr. Hoffa and his teammates came up short, the headline said, "Americans (shot) put in their place."

For Mr. Hoffa and fellow American shot putters Christian Cantwell and Adam Nelson -- Mr. Hoffa finished seventh, Mr. Cantwell won the silver, but Mr. Nelson failed to make a qualifying throw in the final -- the sting came from falling short in such an important setting, not from the fact that the gold went to someone from Poland, Tomasz Majewski, and the bronze to a Belarusian, Andrei Mikhnevich.

"It's the U.S. against the world. Very much so," Mr. Hoffa said. "I really think the Europeans, the Asians, they look to us as the barometer in terms of performance. Throughout the entire year, we always hit big marks. Most big meets we go to, we usually win them all.

"For some reason we couldn't handle the pressure. I know that we're very good throwers, and I'm disappointed we let down a lot of people. I would have never thought that it would have only been one of us" to medal.

In fact, the U.S. track and field contingent has come up short of expectations here.

That leaves it to the many athletes in many other sports to pile up medals -- especially gold -- for the United States to keep up with China.

"The Chinese are so dominant," Carlos Boozer of the Utah Jazz and the U.S. men's basketball team said, "but we're going to do a great job of trying to catch them in the medal count."