Jessica Ennis overcame a slow start to lead the heptathlon after the first day of the World Championships in Daegu.
Defending champion Ennis was disappointed after the hurdles and high jump but hit back to record her second-best ever first-day points haul.
She set a new shot put personal best of 14.67m to regain top spot then clocked 23.28 seconds to win the 200m.
"Normally I lead from the start but I had to work really hard to get that lead," she told BBC Radio 5 live.
"I had to channel the frustration into the next event and thankfully I threw a PB and got some points back.
"I want to relax, get a good sleep and come back strong."
Ennis, who is bidding to be the first Briton to defend a world title, suffered her first heptathlon 110m hurdles defeat since the 2006 European Championships, although she was second-fastest in 12.94 secs despite hitting several barriers
In the high jump she then took two attempts at 1.80m and 1.83, and a nail-biting three at 1.86 before failing at 1.89. She improved her previous outdoor shot put best by 42cm to climb into the lead and tightened her grip on top spot with a formidable run in the 200m.
Ennis leads by 151 points from Russia's Tatyana Chernova, who took Olympic bronze three years ago, with US star Hyleas Fountain third overall, 191 points behind Ennis, with Olympic champion Nataliya Dobrynska fourth, 19 further back.
Great Britain's Commonwealth champion Louise Hazel stood 16th after personal bests of 13.24s in the hurdles and 1.74m in the high jump followed by 12.36m in shot and 24.25 in the 200m.
Tuesday's second day begins with the long jump and javelin, followed by the 800m in the evening session.
British 400m hurdlers Dai Greene, Jack Green and Nathan Woodward all qualified for the semi-finals during Monday's morning session, with Greene fastest overall in 48.52 seconds.
"I felt I didn't want to expend too much energy in the heats but I didn't think I was going to be that fast," said the Welshman.
"At the same time I felt very controlled out there.
"My preparation has been superb coming into the competition. I'm very confident and I feel on track to do myself justice."
Perri Shakes-Drayton was comfortable in qualifying for the semi-finals of the women's 400m hurdles and Eilidh Child also made it through.
Brett Morse was the 12th and final qualifier for the discus final but fellow Britons Carl Myerscough and Abdul Buhari were eliminated.
Jeanette Kwakye finished sixth in her 100m semi final - the best ever performance in the event by a British woman at the Worlds.
But she said of her 11.48 seconds: "It was a slow time and I could have easy qualified for the final so I'm disappointed."
Martyn Rooney, a 2008 Olympic 400m finallist, was unsuccessful in his bid to reach the final here, coming in seventh in his semi-final, admitting: "It was terrible".
And Steven Lewis set a season's best of 5.65m in finishing ninth in the pole vault behind Poland's Pawel Wojciechowski.