BEIJING — The human exodus driven by the misery that followed the Vietnam War has given America some of its most vibrant immigrant communities, but hopes that the wave of refugees from Southeast Asia would help America win Olympic medals were dashed on the badminton court here yesterday, at least for this year.

On Tuesday, a Vietnamese-American, Howard Bach, 29, and a Laotian-American, Khankham “Bob” Malaythong, 27, defeated a team from South Africa to win the right to face off against the no. 2-seeded Chinese team. The quarterfinal match yesterday was America’s first since the sport joined the Olympic roster in 1992, but the unrelenting Chinese opposition ultimately proved too formidable, defeating the Americans, 21-9, 21-10.

The Chinese pair, Cai Yun and Fu Haifeng, pushed Bach and Malaythong to an early deficit, shutting them out, 8-0, before the Americans were able to get their first point on the board. They never recovered in that set, but fared better in the second, where they managed to post a one-point lead three separate times before the Chinese team closed out the game with a 14-point surge that the Americans countered with only two.

“Obviously, they’re world class players and we expect nothing less. They step on the court and every open opportunity they had, they executed. We set up shots great. We had the rallies going. We couldn’t convert,” Bach said.

Malaythong said he did not think jitters led to the Americans’ weak start. “We were just playing a game and they just didn’t make any mistake, you know? I mean everybody makes mistakes. And it takes them a while,” he said in response to a question from The New York Sun.

The U.S. team was on the defensive through most of the contest, though Bach and Malaythong pointed out that they returned most of the Chinese pair’s rapid-fire slams. “We just had confidence that we can hang with these guys and it’s just too bad that the score didn’t show,” Malaythong said.

Several times during the match, when a band of about a dozen Americans high in the stands began chanting “U.S.A.,” Chinese fans responded with loud booing. By the standards of professional baseball, basketball, or soccer, the reaction was mild, but it was an unusual breach of the graciousness China has shown at the Olympics.

“I wouldn’t call it bad sportsmanship, but they just wanted everything and wouldn’t give anything,” Bach said later. “That’s just how the crowd is in any country.”

The hometown audience also unleashed deafening cheers of “jia you,” meaning “fire it up,” or, literally, “add oil.” However, the Americans may have benefited from the fact that about half the 7,500 seats were empty, despite claims that this and nearly all other Olympic events were sold out. “At least they didn’t know how to speak English. It was just Chinese. They couldn’t bad-mouth us,” Bach said.

Bach emigrated to America from Vietnam in 1982 at age 3, after his father was jailed by the communist government there. They lived in San Francisco, where the younger Bach picked up badminton at a YMCA. His father is now back in Vietnam and missed yesterday’s match because of delays getting a visa.

“I really wanted him to come and watch me play, because he missed out on Athens and this might be my last Olympics. Sorry, Dad,” the younger Bach said.

Malaythong came to America in 1990 at age 8, so malnourished that his belly was distended.

Yesterday, the émigrés showed moments of playfulness and frustration. Disappointed with one late-game rally, Malaythong threw his racket high into the air. After another bad break, Bach kissed the lens of a television camera.

Table tennis is viewed by many in the West as the quintessential Chinese sport, but badminton may be played even more frequently here. It’s hard to play ping-pong without a table, but badminton can be played anywhere, even without a net. On a summer evening in China, it’s common to see people swatting the shuttlecock back and forth on the sidewalk.

However, the casual, street version of the sport has little resemblance to the aggressive play on the professional circuit, where slams can be lightning fast. Fu, one of the U.S. team’s opponents yesterday, set the speed record with a slam clocked at 206 miles an hour in 2005.

China is a major force in badminton, having racked up 22 Olympic medals in the sport. Some other Asian countries, such as Korea, Malaysia, and Indonesia also have strong programs, as does, curiously, Denmark. Bach and Malaythong said yesterday they hope their successes at and before the Olympics will help increase the visibility of a sport still obscure in America. “We felt like we came a long way,” Malaythong said.