Wayde van Niekerk booked a place in the IAAF World Championships 400 metres semi-finals, while Dafne Schippers was beaten in her 100m heat during Saturday's opening session in London.
Van Niekerk is being tipped as the next superstar of athletics with Usain Bolt hanging up his spikes at the end of the competition and he got his double bid off to a comfortable start.
Things were not as routine for Schippers in the 100m, but Elaine Thompson did not let some wet weather get in the way of her quest for a first individual gold at a World Championships.
VAN NIEKERK IN CRUISE CONTROL
Reigning world and Olympic champion Van Niekerk barely had to step out of second gear to advance to the 400m semi-finals.
He coasted down the back straight before accelerating out of the final bend to finish first. With the 16th-quickest time of 45.27 seconds, he will be pleased to have got the job done easily as he looks to complete a double with the 200m.
The fastest man of the heats was Isaac Makwala, who beat LaShawn Merritt - a winner of six successive 4x400m relay World Championship golds - in 44.55s, and he hopes to go up against Van Niekerk for gold.
Botswana's Makwala said: "Wayde van Niekerk is my brother. We want to conquer the world together and make the final for Africa. He is so friendly and a lovely guy."
ONE UP FOR THOMPSON
Rain poured down just before defending Olympic champion Thompson's heat but she was unfazed, steaming clear to win in 11.05s.
The downpour had stopped when her gold-medal rival Schippers entered the track for the fourth heat, but, in the lane that contained the most standing water, Maria-Josee Ta Lou beat her across the line.
The Dutchwoman will be eager to improve after failing to make the most of a strong start.
Gina Luckenkemper was the only woman to dip below 11 seconds. The 20-year-old German's 10.95s run provided a personal best and marked her as one to watch in Sunday's semi-finals.
THIAM STARTS ON A HIGH
Nafissatou Thiam is hoping to assert herself as the dominant force in the heptathlon following Jessica Ennis-Hill's retirement.
The Belgian beat Ennis-Hill to Olympic glory in Rio and her high jump prowess put her in command after two events in London.
Thiam was 11th after the 100m hurdles but dominated the first field event - one of her specialties - by clearing a height of 1.95m to go first with 2215 points.
She was pushed by Cuba's Yorgelis Rodriguez, who beat her personal best in the high jump no less than three times to put herself eight points adrift in second. After matching Thiam on 1.95m, she retired from the event and Thiam was unable to go any higher.
IN AND STRAIGHT BACK OUT
Reigning world and Olympic women's hammer throw champion Anita Wlodarczyk only needed one attempt to advance to the final, a throw of 74.61m guaranteeing qualification.
The case was the same for Ryan Crouser in the men's shot put as he looks to add a world title to his gold medal at Rio 2016, but Tomas Walsh outdid him with his first score of 22.14m a season's best.