Justin Gatlin showed a few signs of tiredness after eight hard races in six days but still completed a World Championships sprint double as poor weather conditions continued in Helsinki last night.
Gatlin showed no mercy to any of his opponents over 200 metres, romping to victory in 20.04 seconds to become only the second athlete ever to win the 100m and 200m gold medals in the same Championships.
Team USA's Maurice Greene achieved the feat six years ago in Seville.
Wallace Spearmon finished second in 20.20sec, with defending champion John Capel's season's best of 20.31sec earning him third.
After achieving his pre-Championships intention of winning both titles, Gatlin said: "I wanted to go out there and flick a switch but I had to hold myself back until about the halfway point and then flicked the switch.
"It was more of a surprise to win the 200m, as the guys have been running very well this year. It's a little harder and it's a lot of track. I've shown everybody that I am the best of all sprinters around. I have shown I am a great athlete at 100 and 200m."
On an outstanding evening for the United States squad, further gold medals were won by Michelle Perry in the 100m hurdles, and triple jumper Walter Davis.
Perry, an Olympic heptathlon competitor last year, could not believe how quickly she has successfully made the transition from the multievents back to hurdling.
This year's world's No 1 finished ahead of Jamaican pair Delloreen Ennis-London and Brigitte Foster-Hylton by one-hundredth-of-a-second in 12.66sec. Davis produced his winning leap - a season's best of 17.57m - in the third round to clinch victory ahead of pre-event favourites Yoandri Betanzos and Marian Oprea.
Dutchman Rens Blom was an unexpected winner of a very low-key men's pole vault, clearing 5.80m at his first attempt, while Franka Dietzsch (Germany) regained the women's discus title she won six years ago with a season's best of 66.56m.
James McIlroy gave the beleaguered Great Britain squad some much-needed encouragement after a tactically astute performance saw him qualify for the semi-final of the 800m in one minute 46.44 seconds.
McIlroy's display was particularly welcome after news that Nicola Sanders had been disqualified in the 400m hurdles semi-finals.
The 23-year-old had put up a battling display to come in sixth but was later disqualified because her trailing leg had failed to clear the hurdle.
Sanders is hoping to be included in the 4x400m relay.
Today sees a busy schedule for Great Britain with Tim Benjamin looking to boost the team in the 400m final and the 4x100m squad will start their attempt to add the world crown to their Olympic title. Nigeria, Trinidad and Tobago and Italy look to be the main dangers in their heat.
Birchfield Harrier Mark Lewis-Francis, who was eliminated in the second round of the individual event here, has been included following successful treatment for a hamstring injury with Jason Gardener and Coventry's Marlon Devonish as three of the victorious Athens quartet are joined by Christian Malcolm.
However, the squad will have to display hitherto undiscovered levels of form if they are to finish among the medals.
Goldie Sayers should be more than capable of making the final of the javelin after setting a personal best of
61.45m at the European Cup in June, while Chris Tomlinson will attempt to reach the long jump final despite being prevented from competing outdoors this season by injury.