Provided by IAAF

The new and the old, the unknown and the known; the two semi-finals of the women’s 1500m were contrasting affairs.

Four of the five automatic qualifiers from the first semi-final – Zoe Buckman, Faith Kipyegon, Elena Korobkina and Mary Cain – have yet to make a big impact on the event; four of the five from the second – world leader Abeba Aregawi, World indoor 3000m champion Hellen Obiri, defending champion Jennifer Simpson and Daegu 2011 silver medallist Hannah England – most definitely have.

You can stretch analogies too far, and in the end each championship comes down to one race on one day, but there did seem an air of difference about the two races.

The difference was emphasised by the presence of Cain in the first heat. Already, at 17 years, three months and 10 days, she is the youngest finalist in the history of the women’s 1500m at the World Championships.

The first semi-final was also balanced by the presence of Nancy Langat, the Beijing 2008 Olympic champion, but as she went through to Thursday night’s final only as the fastest non-automatic qualifier perhaps she does add to the generational change argument after all.

Luiza Gega, the Albanian record-holder, ensured the first semi-final went off at a solid pace, taking the field through 400m in 1:03.33 and 800m in 2:12.01.

At the bell, Genzebe Dibaba was a narrow leader, with Australia’s Buckman on her inside and Siham Hilali and Obiri close up in a bunched field.

Dibaba led into the straight just as Buckman squeezed through on the inside of a tiring Hilali. Now it was a battle between Buckman on the inside and Kipyegon, second on this year’s world list with 3:56.98, on the outside.

At the line, Buckman – who surely has not run more than a total of 3000 metres in heat and semi, showing the value of keeping inside – was centimetres clear in a personal best 4:04.82 to Kipyegon’s 4:04.83.

To the delight of the crowd, Russia’s Elena Korobkina took third in 4:05.18 with Cain, who this time had raced in the first half of the field all the way, next in 4:05.21 and Dibaba fading to the fifth and final automatic spot in 4:05.23.

Ultimately, Langat and Hilali, the next two across the line, made the final as the two fastest non-automatic qualifiers.

The second semi-final was led by Russia’s Ekaterina Sharmina through 400m in 1:06.87 and 800m in 2:15.76, slower than the first.

By 1200m, Aregawi, the fastest in the world this year at 3:56.60, was in the lead after a 65.38 third lap and she then produced a 44.52 final 300m to hold off Obiri and Simpson all the way to the line.

Aregawi represented her native Ethiopia at the London Olympics, but is now running for Sweden where she has lived since 2002. She ran 4:05.66, Obiri was second in 4:05.76 and Simpson third in 4:05.79. Narrow margins, but you got the impression they would have closed them if they could have. We shall see.

Sharmina held on to fourth place in 4:06.49 and England reprised her Daegu run with a strong finish to take fifth in 4:06.80, more than a second clear of Canada’s Kate Van Buskirk in sixth.

Missing the final was Daegu bronze medallist Natalia Rodriguez, who finished eighth in 4:09.18.

Len Johnson for the IAAF