Lang received a great reception from the Chinese crowd
Former China player Jenny Lang Ping coached her United States side to a 3-2 win over her old team to earn the US a place in volleyball's quarter-finals.
The US lie second in Group A following their 23-25 25-22 23-25 25-20 15-11 victory over the Olympic champions.
Group leaders Cuba beat Japan 3-0 while Brazil and Italy recorded 3-0 victories over Kazakhstan and Serbia respectively to take the Group B title to the wire.
Poland beat Venezuela 25-12 25-12 25-20 for their first Group A victory.
Chinese President Hu Jintau was present for China's defeat to the US.
Lang helped lead the Chinese team to international prominence as a player as they won the gold medal at the 1984 Los Angeles Games, and was met by thunderous applause when her name was announced.
But Lang's US team soon quietened the crowd, levelling their 2-1 set deficit after a Chinese error and gaining momentum in the fifth to earn the win.