Jessica Ennis-Hill has one hand on heptathlon gold with just the 800m to go but fellow Briton Katarina Johnson-Thompson’s medal hopes are over after she fouled out of the long jump.
Johnson-Thompson, 22, recorded no jumps in the first two of her three attempts but then appeared to have rescued it with a huge leap in the third.
But after protracted and despairing discussions she was ruled to have marginally fouled that one too, and with no points from the fifth discipline her competition was effectively over after five events despite a later team appeal.
Ennis-Hill recorded a season’s best of 6.43m, just nine centimetres off her personal best, and then threw 42.51m in the javelin to open up a gap of 86 points over the Netherlands’ Nadine Broersen in the silver medal position, with world number one Brianne Theisen-Eaton of Canada in third.
That equates to a cushion of just under six seconds in the 800m, where her personal best is three and a half seconds faster than Broersen’s and more than a second faster than that of Theisen-Eaton.
Ennis-Hill’s prospects improved further when Commonwealth champion Theisen-Eaton appeared to pick up an injury during the javelin.
Ennis-Hill, 29, is competing at a major championships for the first time since London 2012, and – having only given birth to son Reggie in July last year – a gold medal here would arguably be more impressive even than her Olympic triumph.
But a British one-two, which appeared a genuine possibility after the first day, will now not happen after Johnson-Thompson’s disastrous morning.
So big was her third attempt, in what is her strongest event – she is also competing in the individual long lump later in the week – that had it been called good it would have established what might have been an unassailable lead in the overall competition.
With Ennis-Hill having nailed her own effort in the second round it was arguably a gamble worth taking. Initially it appeared to have paid off.
But the officials spotted the tiniest scuff mark in the plasticine beyond the take-off board and although Johnson-Thompson protested its legality, officials decided after three minutes of argument that it would not be measured.
The young Briton had almost fouled out of another of her strongest events, the high jump, on the first morning, only clearing the relatively modest 1.80m at the third and final attempt.
And although she came out for the javelin competition – despite falling down to 30th place overall – as the appeal continued, her demeanour told its own story.
After a fine first day – a personal best of 13.37secs in the 100m hurdles, another with 12.47m in the shot before an impressive 23.08secs in her first 200m of the season – she looked set to go head-to-head with Ennis-Hill in what was shaping up to be an epic 800m.
To miss out on a World medal in such circumstances will be chastening, yet with the Rio Olympics a year away it is also a valuable lesson for a young athlete with a huge future.
Ennis-Hill, by contrast, has been relentlessly consistent – a solid 12.91secs in the 100m hurdles, an equal season’s best with 1.86m in the high jump, 13.73m in the shot put and 23.42 seconds in the 200m.
Britons prosper in quick conditions
produced a personal best of 44.45secs – the fastest time ever run by a Briton at a Worlds – to qualify from the 400m heats, although the extraordinary level of competition meant that time was only enough to see him through as a fastest loser.
As 18 men went under 45 seconds, Rooney finished fourth in a heat won in 43.93secs by Yousef Masrahi, with British champion
also through by virtue of winning heat five in 45.24secs.
qualified in some style from the heats of the 400m hurdles, Beesley in a new personal best of 54.52secs.
is into the 100m semi-finals after coming home third in 11.28secs behind an impressive 10.88 from the USA’s Tori Bowie.