"Boys cry, too," Lin said on Sunday after he became the first man to win two Olympic singles titles. "He couldn't control his tears. I rarely see him cry so he must be very emotional."
Li Yongbo's overwhelming joy also came from seeing something neither he nor anyone else has seen.
A sweep of all five badminton gold medals in the Olympics.
After winning the men's and women's singles and doubles and mixed doubles at the last two world championships, China became the first team to do it in the Olympics.
They missed out in Beijing when Cai Yun and Fu Haifeng lost the men's doubles final, but Cai and Fu came through on Sunday, the first Chinese men to win the doubles.
The entire team and coaches celebrated in Wembley Arena after most of the sellout crowd had gone, by forming a circle on the court and cheering and bowing to the few fans left. They then posed for group photos on the podium and let Li Yongbo wear every gold medal.
Asked if China's domination was good for the sport, Lin Dan was unequivocal.
"The Chinese team made their best personal efforts," he said. "As players we all have responsibility to achieve the best results and defeat our rivals. We don't need to consider anything else."
Lee Chong Wei of Malaysia, whom Lin beat in the final for a second straight Olympics, agreed with his friend.
"I congratulate China," Chong Wei said. "It's total domination. It's good for China but for the rest of the countries, they have to start working harder.
"China produce a lot of players, they have a succession plan. Other countries don't have a succession plan."
Chong Wei gave Malaysia some relief besides his second silver medal by putting off his retirement until 2014 so he can finally win a world championships title. He's been denied in the era of Lin Dan, who also ruined Chong Wei's Olympic hopes by winning their gripping final 15-21, 21-10, 21-19.
"There's only one Lin Dan in the world," Chong Wei graciously conceded.
Chong Wei, on painkillers after tearing ankle ligaments 10 weeks ago, was under tremendous pressure to deliver Malaysia's first-ever Olympic gold medal. Afterwards, he told his country and fans, "I'm sorry."
But of Malaysia's three silver medals, he now owns two of them as their most successful Olympian.
"He's such a brilliant rival that I am quite lucky," Lin said. "I treasure the opportunities of playing him."
The teammate groomed to succeed Lin, Chen Long, won the bronze from Lee Hyun-il of South Korea, who also lost the bronze playoff in Beijing. Lee Hyun-il, who retired after Beijing but was persuaded to return by desperate Korean officials in 2010, accepted the result with uncommon calm.
"I tried my best and I played as well as I can so I don't have any regrets," Lee said. "I now feel relieved it is all over."
Cai and Fu then took the court and weren't willing to accept the same fate as Lee Hyun-il.
The four-time world champs routed Mathias Boe and Carsten Mogensen of Denmark 21-16, 21-15.
"Last time in Bejing we only achieved silver. We regretted that," Cai said. "Because it is the men's doubles, we were expected to do better by our country. For this match we were not afraid of failure, we tried to enjoy it. Part of the reason we won was we were full of confidence."
With their Queen Margrethe watching in the stands, Boe and Mogensen were happy to settle for silver.
"China are the No. 1 badminton nation," Mogensen said. "It is a little bit annoying that they are as good as they are, but it is a well deserved win for China."
Lee Yong-dae won his second Olympic medal, after a mixed doubles gold in Beijing, when he and the retiring Chung Jae-sung won the bronze for South Korea from Koo Kien Keat and Tan Boon Heong of Malaysia 23-21, 21-10.