Perri Shakes-Drayton and Eilidh Child both eased through to the final of the women's 400m hurdles at the World Championships in Moscow.
British champion Shakes-Drayton clocked 53.92 seconds, the second quickest qualifying time of the semi-finals.
But Dai Greene's defence of his 400m hurdles world title ended with a fifth-place finish in his semi-final.
The Briton, who has suffered injury and illness in recent months, struggled home in 49.25 seconds.
"I just didn't have it in the tank," admitted the 27-year-old Welshman.
Greene's failure to make an impact in the Russian capital is of little surprise because he was blighted by an Achilles tendon problem in the run-up to the championships and had to overcome illness prior to his heats.
"Things were going well up until the last few weeks. This championship came a week too early - maybe another week and I would have been able to get up there," added the Swansea Harrier.
His compatriot Rhys Williams also failed to progress, a fourth place in 49.29 was the best he could manage, while fellow Briton Sebastian Rodger was sixth (49.32) in the first semi-final.
At the other end of the spectrum, Shakes-Drayton has performed like a potential medallist throughout the season and looked strong as she overtook defending champion Lashinda Demus on the home straight.
"I feel good," she said. "I would love to come home with some kind of bling but we won't say too much, we will just wait and see."
Shakes-Drayton, 24, will go head-to-head with Czech gold medal favourite Zuzanna Hejnova in Thursday's final, with the world number one the fastest qualifier in 53.52.
The race will be a first global outdoor final for Shakes-Drayton after she missed out at London 2012
Child was the fifth fastest qualifier in 54.32, while Meghan Beesley did not make it to the final but did run a lifetime best 54.97 to finish sixth in her heat.
Elsewhere, Andrew Osagie, another Briton who has had injury problems, clocked one minute 44.36 seconds, his best time of the year, to finish fifth in the 800m final.
"I never thought the day would come when I was happy finishing fifth, it was slightly better and quicker than I expected," said last year's Olympic finalist, who failed to compete at the British Championships because of a hamstring injury.
"I am happy, but frustrated I couldn't get a medal. There was probably a medal available if I was in my lifetime-best shape but I wasn't."
Eilish McColgan, who has suffered with a shin injury, came 10th in the 3,000m steeplechase final.
"If you had told me that a week ago I would have taken it, but after running it I just feel there was more to give," said the 22-year-old Scot.
"Top 10 in the world is more than I thought I would get but I've ran two personal bests and need to be happy with that."
Hannah England will line up in the women's 1500m final after securing the fifth qualifying spot in four minutes 06.80 seconds.
"The heat was so close earlier and it made me nervous," said the 2011 silver medallist. "I got tense in the last 100m thinking someone was going to pass me.
"I was thinking all day today that the only final I had failed to make was the Olympics last year so I just wanted to keep up my record."