Beijing: Tirunesh Dibaba of Ethiopia produced a trademark electric last lap to win the Olympic 10,000 metres gold on Friday and keep her unprecedented bid for a long-distance running double on target.
In the other medal, Tomasz Majewski of Poland gatecrashed the shot put competition, taking gold and with it any chance of US putters extending their Olympic dominance of the event.
Dibaba, the reigning double world 10,000m champion, set a new Olympic record time of 29min 54.66sec in perfect conditions at a packed National Stadium.
She had been happy to follow the race leaders for all but one of the 25 laps, but as soon as the bell for the final lap sounded, she opened up and pulled away with ease from silver medallist Elvan Abeylegesse, the Ethiopian-born runner representing Turkey.
American Shalane Flanagan won a shock bronze medal in 30:22.22.
"I have won gold in the world championships many times but I was expecting something really special at the Olympics and I got it. I'm delighted," said the 23-year-old.
Dibaba added that a decision on doing the double was yet to be made.
"I haven't decided whether I will run the 5000m yet," she said.
In the shot put, Majewski threw a personal best of 21.51m, American world indoor champion Christian Cantwell taking silver with 21.09 and Andrei Mikhnevich of Belarus the bronze, 4cm adrift.
American world champion Reese Hoffa could only finish seventh while two-time Olympic runner-up and compatriot Adam Nelson fouled out, frustrating US bids to build on their event record of 17 golds in 26 Olympic Games.
On the track, Jamaica's 100 metres world record-holder Usain Bolt sent out a message of intent to his rivals for the Olympic crown with an effortless run of 9.92 seconds to qualify for the semi-finals.
Bolt shot off from the blocks and after taking the lead on 50 metres, eased up and mockingly flicked his head from one side to another as he posted the sixth best time of the year.
His compatriot Asafa Powell, from whom he snatched the world record in May, also won his heat in style, easing up at 10.02sec.
But American reigning double world champion Tyson Gay, who has been off the Grand Prix circuit for more than a month recovering from a hamstring injury, could only finish second in his heat at 10.09sec.
The trio's predicted dominance in the blue-riband event, however, could well come under threat from a raft of pretenders to the title.
Churandy Martina of the Dutch Antilles and Richard Thompson of Trinidad both clocked 9.99sec in their respective heats, and could well be in the medal mix if they can continue that form into Saturday's semis and final.
American Hyleas Fountain was in control after the first day of the heptathlon despite a terrible showing in the shot put.
Fountain, who failed to finish the world championships in Osaka last year, fell back on her strengths to notch up 4060 points for the day.
The American recorded lead times in the 100m hurdles (12.78sec) and 200m (23.21sec) as well as the joint lead in the high jump of 1.89m
She could manage only 13.36m in the shot put, almost four metres behind Ukraine's Nataliia Dobrynska, who dropped into second overall after a 24.39sec in the 200m, 64pts adrift of Fountain.
Pre-event favourite Kelly Sotherton of Britain moved into third place on 3938pts thanks to a 200m in 23.39sec.
Russian Anna Bogdanova was in fourth on 3922pts with Ukraine's Lyudmila Blonska once place further back on 3912.
The second day of the heptathlon on Saturday sees the women going head-to-head in the long jump in the morning, before competing in the javelin and climaxing with a strength-sapping 800m.
The reigning heptathlon champion Carolina Kluft, who opted not to defend her title, failed in her attempt to reach the triple jump final.
The 25-year-old finished 20th in qualifying and will now seek consolation in the long jump, an event in which she finished 11th in the 2004 Olympics.