Briton Mo Farah continued his impressive track form by claiming a hard-fought victory in the world 10,000m on Saturday, as Jamaican sprint star Usain Bolt cruised through his 100m heat.
Farah, who is attempting to replicate the double 5,000-10,000m gold he claimed at last year's London Olympics, had a slow race pace, American training partner Galen Rupp and his own definitive race-end kick to thank for his victory.
There was an all-too-familiar finish to the 25-lap race when Ethiopia's defending world champion Ibrahim Jeilan tried to edge past Farah on the final bend.
Two years ago in the Daegu worlds, Farah wilted into second behind the sprint-clever Ethiopian, but a season dedicated to honing his speed this time paid dividends.
"It was the perfect race for me," the Somali-born Farah said. "It was quite slow, and the important thing was to stay out of trouble."
With Jeilan and his three teammates plus a strong Kenyan line-up, Farah said he and Rupp, who both train in Oregon, Portland, with Alberto Salazar, had tried "to work together and to cover every move".
"Two years ago, almost exactly the same thing happened (around the final bend). It was important I had something left on the final lap."
Jeilan took silver and Kenyan Paul Tanui bronze, Rupp just missing out on the podium in fourth.
Track icon Bolt, within touching distance of equalling American sprint legend Carl Lewis' record of eight world gold medals, clocked an easy-going 10.07sec in his heat of the 100m, which featured neither American rival Tyson Gay nor Asafa Powell after both tested positive for banned substances.
The Jamaican saw teammate Yohan Blake claim victory in Daegu after his shock false start in the final, the one blip on his impressive CV, that includes Olympic gold in the 100m, 200m and 4x100m relay events in Beijing and London, and five world titles, as well as the 100 and 200m world records.
Bolt will be joined in Sunday's semi-finals by American rivals Justin Gatlin, the 2004 Olympic champion, London bronze medallist and double world champion in 2005, and Mike Rodgers, who have both served doping bans.
The duo were the only sprinters to clock sub-10sec times to serve notice that Bolt will not have it all his own way.
"I am happy with my run," said Bolt, who survived a false start in his heat. "I took it easy as it was the first round. I just wanted to get my reaction and start right.
"The false start in my heat didn't affect me. I made that mistake in Daegu and now I'm staying focused."
The second gold on offer on the opening day of competition went to Tanui's teammate Edna Kiplagat, who became the first woman to defend the world marathon title.
The 33-year-old, who could only finish 20th in the London Olympics last year, timed 2hr 25min 44sec to take gold ahead of long-time leader Valeria Straneo of Italy (2:25.58) while Japan's Kayoko Fukushi took bronze (2:27.45).
