Silas Kiplagat produced the shock result of the International Association of Athletics Federatons (IAAF) Diamond League meeting as he outsprinted the Kenyan compatriot who had been targeting a world record in the 1500 metres, Asbel Kiprop, to win in 3min 27.64sec, making him the fourth fastest man in history.
It was the second outstanding middle distance race of a warm evening ideal for athletics following an 800m which saw another surprise as world record holder David Rudisha faded to fifth in a race won in a 2014 world-leading time of 1:42.45 by Botswana's Nijel Amos, with Pierre-Ambroise Bosse setting a French record of 1:42.53 in second place.
Elsewhere in the programme, Caterine Ibarguen produced the best triple jump of the last six years in registering 15.31 metres, which put her fifth on the world all-time list, 19 centimetres shy of Inessa Kravets's world record of 5.50 set at the 1995 IAAF World Championships.
The Colombian needed something big in her final effort to wrest back the lead from Russia's Yekaterina Koneva, whose second round personal best of 14.89m had bettered Ibarguen's first round effort by 11cm.
Koneva's effort also bettered Ibarguen's 2014 world-leading mark by two centimetres.
"I never doubted my chances of winning," she said.
"I never lost faith.
"The world record is there - it's not far.
"I will strive and fight for it."
Kiplagat's mark was, of course, the best run this year, and a Diamond League record, trimming 0.08 off the time Kiprop set in winning here last year.
For the double world champion, who finished in a season's best of 3:28.45, it was a huge anti-climax after he had prepared for this attempt on Hicham El Guerrouj's 16-year-old mark of 3:26.00 by setting the fastest 800m time of the year, 1:43.34, at the Paris Diamond League meeting earlier this month.
"At 1200m I knew the race was too slow," Kiprop said.
"We went through in 2.47 and I had asked for 2.45. In the home straight I could see the others behind me on the big screen and I knew they would get back on me. I could see Silas coming closer and closer.
"It was a tough race."
As for Kiplagat, he is now thinking in terms of mounting a world record attempt himself.
"I have the fast time now, but why not be faster and attack the world record?" he said.
"I'm still young and ready to train for it.
"I always run well here, so I'm thinking my win and result is no surprise.
"I was aware I can do it."
As he had hoped, Rudisha, returning from a year off injured, managed a 1.42 clocking here.
But that was only enough to earn the Kenyan Olympic champion fifth place in a stupendously competitive race won by the man who followed him home at London 2012, Amos, in a time that was also a meeting record.
Bosse, who had spoken beforehand of the possibility of defeating Rudisha ("he's not a God"), took second place in a French record of 1:42.53 which underlines his status as favourite at next month's European Championships.
As he rounded the final bend in the lead it looked as if Rudisha, who had equalled the 2014 world lead with victory in 1:43.34 in the previous Diamond League meeting at Glasgow, was all set to secure another morale-boosting win.
But as he entered the final straight the smaller figure of Amos moved out to pass him in lane two, teeth bared with the effort.
Rudisha was unable to respond, and in the final 20 metres the roars redoubled as Bosse moved through, closing on the Botswana athlete, but running out of room.
As Rudisha faded, two others moved past him in the final 10 metres - Ethiopia's world champion Mohammed Aman, who clocked a season's best of 1:42.83, and Kenya's Ferguson Rotich Cheruiyot, who finished fourth in a personal best of 1:42.84.
Bosse's was the first of two French records on the track as his flourish was matched by Pascal Martinot-Lagarde, who won the 110m hurdles in 12.95sec, his first sub 13 second clocking.
American athletes provided three out of the seven 2014 world-leading performances on the night, thanks to sprinters Justin Gatlin in the men's 200m in 19.68sec, Tori Bowie in the women's 100m in 10.80 and Ajee Wilson, who inflicted the first defeat of the season on world 800m champion Eunice Sum as she won in 1:57.67, with the Kenyan second in 1:57.92.
Genzebe Dibaba overcame a powerful challenge from her Ethiopian compatriot Almaz Ayana to record a 2014 world-leading time of 14:28.88 in the first Diamond League women's 5,000m to be held in Monaco.
In a men's high jump which boasted six men who have cleared 2.40m or higher this year, Ukraine's world champion Bogdan Bondarenko proved superior, being the only man to clear 2.40 on the night.
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