Jessica Ennis will take a slender lead into the final two events of the pentathlon on Friday night as she looks to defend her title in the World Indoor Championships in Istanbul.
Ennis made the perfect start with victory in the 60 metre hurdles and then salvaged a respectable performance in the high jump with a clearance of 1.87m at the final attempt.
Her lead of 109 points looked set to be wiped out in the shot, but the 26-year-old responded superbly with a new personal best of 14.79m to claim a 10-point lead over Lithuania's Austra Skujyte going into the long jump and 800m.
Olympic champion Nataliya Dobrynska is a further 19 points adrift in third, with Russian Tatyana Chernova - who took Ennis' world heptathlon title in Daegu last year - surprisingly 184 points behind the Briton in fifth.
"I was happy with the hurdles, slightly disappointed with the high jump, but to throw a PB in the shot and hold onto my lead was brilliant," Ennis said.
"I thought Austra would take the lead in the shot because she's a great thrower and there's normally quite a bit of distance between us. Shot has been going well in training, it's just pulling it out on the day and I think I'm good at getting it out in my third round."
All the talk beforehand had been about the clash between Ennis and Chernova, but the Sheffield athlete added: "I've always said it's not just between me and Chernova, it's Olympic year and everyone raises their game and you could see that."
Elsewhere, Britain's athletes enjoyed a largely successful first morning of competition, with only Marilyn Okoro in the 800m and Lewis Moses and James Brewer in the 1500m failing to advance.
Veteran Yamile Aldama qualified for the final of the triple jump with her first jump of the competition, the 39-year-old recording a season's best of 14.62m to easily surpass the automatic qualifying mark of 14.30m.
Shana Cox and Nadine Okyere both advanced to the semi-finals of the 400m, Nigel Levine and Richard Buck did likewise in the men's event, Joe Thomas and Andrew Osagie also reached the semi-finals of the men's 800m and European indoor champion Helen Clitheroe made the final of the 3,000m.
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