DAEGU, South Korea -- Defending champion Jessica Ennis moved into the lead after four events in the heptathlon Monday at the world championships.
The British athlete finished first in her 200-meter heat and finished the opening day of competition with 4,078 points. Tatyana Chernova of Russia was second with 3,927 points while Hyleas Fountain of the United States was third with 3,887.
Ennis was out of action for seven weeks earlier this season with an ankle injury but has looked strong since returning to competition in mid-May.
Fountain had a 41-point lead over Ennis after the 100-meter hurdles and high jump early Monday but Ennis moved in front after the 200 and a seventh-place finish in the shot put.
"I'm happy with how the high jump and hurdles went and definitely not happy with shot put and 200," Fountain said. "But I have enough time to sleep it off and come back tomorrow."
The heptathlon concludes on Tuesday with the long jump, javelin and 800.
The 25-year-old Ennis still has a chance to become only the fourth woman in history to break the 7,000-point barrier in the seven-discipline event.
Only three women -- Jackie Joyner-Kersee, Larisa Turchinskaya and Carolina Kluft -- have broken the 7,000-point barrier.
Olympic champion Nataliya Dobrynska was still challenging for a medal. Dobrynska was second in the shot put and fourth in her 200 heat for 3,868 points.