Jessica Ennis-Hill and Katarina Johnson-Thompson towered over their World Championship rivals after the opening two events of the heptathlon in Beijing.
Sheffield’s Ennis-Hill, in her first major championship since London 2012 and 13 months after the birth of her son Reggie, clocked 12.91 seconds over the 100 metres hurdles and then equalled her season’s best of 1.86m in the high jump to lead the way on 2192 points.
Johnson-Thompson lay in second place, 30 points back.
The 22-year-old began a scorching morning at the Bird’s Nest stadium with a personal best of 13.37secs in the hurdles, but lived dangerously in the high jump, one of her strongest events, before finally clearing 1.89m, the only athlete to do so.
Ennis-Hill’s time over the barriers was 0.12secs down on that which she ran at the Anniversary Games in London in her last outing, but it was still a decent return to the world stage.
And the Olympic champion, who only returned to competition three months ago, looked smooth in the high jump with first-time clearances all the way to 1.86m before going no further.
Her team-mate was rather more erratic, needing third and final attempts to get past 1.80m, her opening height, and 1.89m.
The pair are going head to head over seven events for the first time since London 2012.
And there was more good news for them, with world number one and favourite, Canada’s Brianne Theisen-Eaton, enduring a poor high jump, managing only 1.80m, to lie in fifth place, 87 points behind Ennis-Hill.
The shot put and 200m are to come later on Saturday, with the remaining three events the following day.
Elsewhere, Laura Muir, a medal contender in the 1500m, cruised through her heat, finishing second to Ethiopia’s Besu Sado in 4:05.53.
Laura Weightman, the silver medallist at last summer’s Commonwealth Games, also did enough to progress, coming home sixth in her heat in 4:06.13 and fortunately appearing to emerge relatively unscathed from a heavy fall just after crossing the line.
Muir said: “I stayed at the back out of trouble to let things settle down and then came through when it started to speed up a bit. I’m really pleased with the way I did it.”
The news from the 800m was less positive, though, as Michael Rimmer and Kyle Langford both crashed out, but Ireland’s Mark English scraped through as a fastest loser.
Nick Miller qualified second for the final of the hammer, but Mark Dry went out.