Kenyan-born Norah Jeruto won world gold for Kazakhstan in the women's 3000m steeplechase on Wednesday while China's Feng Bin threw a massive personal best to claim the discus title.
While day five of action at Hayward Field featured only two finals, South African heavyweights Caster Semenya and Wayde van Niekerk were trackside along with 400m hurdles stars Sydney McLaughlin and Dalilah Muhammad in a series of high-calibre heats and semi-finals.
Jeruto clocked the third fastest time in history and a championship record of 8min 53.02sec for the steeplechase victory in Eugene, with Ethiopian Werkuha Getachew claiming silver in a national record of 8:54.61.
A second Ethiopian, Mekides Abebe, made the most of a mistake by Kenyan-born Bahraini Winfred Mutile Yavi on the final water barrier, to snatch bronze (8:56.08).
The discus was all but over after the first round as Feng threw 69.12m on her opening visit to the ring, improving by more than three metres her previous best of 66.00m set in Beijing in April.
Croatia's Sandra Perkovic, a two-time Olympic champion and also twice a world gold medallist, claimed silver with 68.45m. American Valarie Allman, who won Olympic gold at the Tokyo Games, took bronze with 68.30m.
Semenya's first appearance in a world championships in five years saw the controversy-mired South African fail to qualify for the women's 5000m finals.
'Cooking' Caster
In roasting mid-afternoon temperatures, the two-time Olympic gold medallist finished 13th in the first of two rounds in 15:46.12, more than 45sec off the 15th and final qualifying place.
"Cooking!" said Semenya, who was forced to switch from her favoured 800m (in which she is also a former three-time champion) to the longer event due to gender eligibility rules that required her to take testosterone-reducing drugs to compete in races between 400m to a mile post-race.
"It was hot, I could not keep up with the pace, I tried to stick as much as I can, but you know, it is a part of the game.
"I think it is great to be able to run here," she added. "Just being able to finish the 5k, for me it is a blessing. I am learning and I am willing to learn even more."
Her time was far off the heat-winning 14:52.64 set by Ethiopian Gudaf Tsegay, fresh from her silver in the 1500m.
Semenya's teammate Wayde van Niekerk qualified for the final of the men's 400m after finishing second in his semi-final in 44.75sec.
Van Niekerk set the world record of 43.03sec when winning Olympic gold in Rio, but then sustained a nasty knee injury that saw him sit out track for three years.
"It is the challenge of doing this 400m and not having as many races in my legs as I would love to have by now," he acknowledged.
"But I made it through and I felt comfortable for the majority of the race. So it is about recovering now and getting ready for the final."
Van Niekerk added: "It is a learning process in every race. I am listening to my body and executing that way.
"It has been a challenging three years and now, I just want to come out and do my best. I need to be back with every step I take to be able to challenge my record."
US one-lap medal hope Michael Norman topped qualifying times for what should be an ultra-competitive final on Friday.
Elsewhere, Sydney McLaughlin underscored her status as favourite to add a world gold to her Olympic 400m hurdles crown as she motored into a final showdown with USA team-mate and defending champion Dalilah Muhammad.
"It's going to be a great race, I know that for sure," said McLaughlin.
Finally, there was bad news for the US men's 4x100m relay team as newly-crowned 100m champion Fred Kerley was ruled out of action.
Kerley was diagnosed with a "slight injury to his quad" in the semi-finals of the 200m, from which he failed to advance.