China took an early lead in the Olympic march to sports supremacy, winning two of the first seven golds when the Beijing Games began in earnest on Saturday.
But the first full day of action was overshadowed by the brutal murder of Todd Bachman, the father-in-law of US Olympic volleyball men's team coach Hugh McCutcheon.
Bachman was stabbed to death at the city's famous Drum Tower which he was visiting with his wife Barbara and daughter.
Mrs Bachman was seriously hurt in the assault, sustaining life-threatening injuries, while the attacker, a 47-year-old man from eastern China, jumped to his death off the second storey of the monument.
Hours after the tragedy, the Games teetered on the brink of more controversy when the 35-member Georgian squad threatened to pull out in protest over Russia's role in the escalating violence in the troubled enclave of South Ossetia.
Those developments came on a day when China's hopes of grabbing the attention-commanding first medal had been dashed.
Shooter Du Li, the defending champion in the women's 10m Air Rifle competition, wilted under the pressure and allowed Czech opponent Katerina Emmons to come through to win with a record-breaking performance.
Pang Wei made amends for China, taking the men's 10m Pistol event and Chen Xiexia won the women's 48kg weightlifting title.
Spanish cyclist Samuel Sanchez won the gruelling road race, Choi Min-Ho won for South Korea in the men's -60kg judo division while Romania's Alina Dumitru claimed the women's -48kg judo gold.
Mariel Zagunis beat compatriot Sada Jackson in the women's fencing sabre final for the United States sole gold of the day.
In the opening session at the pool American ace Michael Phelps opened his quest for eight golds by posting a Games record to a win in his heat of the 400m individual medley.
Phelps was under world record pace for the first half of the race, before easing off to record the fourth fastest time ever.
"I didn't think I'd swim that fast in the preliminaries. I saw the first few heats go out, and I kind of wanted to be the top seed for tomorrow, that is all I went out to do," he said.
The the honour of first on the podium in Beijing went to Emmons who overcame a splitting headache to produce a record-breaking performance in winning the women's 10m air rifle title.
"I couldn't believe it. I had a headache this morning. I felt so terrible that I didn't know how I'd shoot. So to win the first gold medal of this Olympics is pretty amazing," said Emmons who broke Du's Olympic record in the process.
Du, under pressure to produce 'aoyun shoujin' - first Olympic gold - fled the hall in tears, and later said she "wasn't fully prepared for the pressure of competing at home".
But there was no sign of nerves when Chen won her weightlifting gold and set two Olympic records, nor with Pang at the shooting range although team officials did not tell him Du had failed.
"We have to focus on our own performance and this helps me to relax and not come under pressure."
In hazy, hot and humid conditions, Sanchez prevailed in the cycling road race for the biggest win of his career after a tough 6hr 23min 49sec in the saddle and was quick to share the plaudits with his dominant Spanish team.
"My biggest fear was whether we'd be able to control the race as a team, and in such humid, and tremendous heat. But we raced to perfection."
Pre-race favourite and reigning champion Paolo Bettini of Italy was left trailing after a decisive attack on the final climb by Australian Cadel Evans.
That move also dropped co-favourite Alejandro Valverde of Spain, and ultimately led to a six-man finish with Italian Davide Rebellin a close second and Switzerland's Fabian Cancellara third.
There were other controversies on the opening day of the Games.
Greece recalled a track athlete after testing positive for a prohibited performance drug.
Greek officials did not immediately name the competitor but local media revealed it was men's 200 metre runner Tassos Gousis, who denied any wrongdoing.
In Hong Kong, a pro-Tibet activist was forced to leave the equestrian venue where she planned to unfurl a Tibetan flag.