There were a few boos from the packed-out London Stadium crowd as Guliyev streaked through the line ahead of Van Niekerk, thousands immediately upping and leaving rather than savouring the winning moment which ruined the South African's bid to match Michael Johnson, the U.S. track legend who won the double at the 1995 Gothenburg worlds and went on to repeat the feat a year later in the Atlanta Olympics.
Trinidad and Tobago's Kareem Richards came home with a rush in lane seven to take the bronze medal, but Guliyev pushed past the South African favourite in the final 50m to win in 20.09 seconds.
"I will never try and fill Usain's shoes, or Michael's", said van Niekerk.
"This is not a shock, but it does not feel real".
"I definitely deserve way more respect from my competitors".
"I delivered my best race at the right time". I'm so happy to be world champion.
Guliyev was left with the last word, hailing the "best moment of my career".
"I've learned a great lesson now so I'm definitely going to be taking the future by focusing on myself and not letting such negativity get to me".
"I didn't just celebrate the medal I got tonight, it was more a celebration of the competition overall". I wanted to win.
"I thought I could go through in first or second but I'm alright", said Blake.
Olympic and world champion Christian Taylor fended off a strong challenge from American compatriot Will Claye to make a successful defence of the triple jump title.
First Usain Bolt was denied the flawless ending to his career, then fellow veteran Allyson Felix missed out on gold in the 400m and now to cap it off the 200m men's final went against the fairytale as well. It's not like the 400m. "This final was a fight; I enjoyed it". I was ready to run.
"I think it's great for my career", the 400-meter Olympic and world champion said.
LONDON | It wasn't Wayde van Niekerk and it wasn't Isaac Makwala.
"The last 50 meters, I was feeling exhausted".
"Maybe at the next competition everyone will look at me instead".
He took care of the 400m easily earlier in the week but on Thursday night was denied the double by Turkey's Ramil Guliyev.
Taylor's best mark of 17.68 metrers was enough to edge out Claye, who could only manage 17.63m.
"I'm absolutely over the moon, especially after the year that I've had", said Asher-Smith, who fractured her foot in February.
"I was competing against some of the best athletes in the world, so it didn't bother me that the attention was on them". But with all eyes elsewhere, Guliyev ran his own race and earned the ultimate prize.
Muhammad had to settle for the silver medal in 53.50 as her wait for a World Championships gold medal continues.
Chris O'Hare and Jake Wightman qualified well for the 1500m semi-finals, with all three British women in the 800m - Lynsey Sharp, Shelayna Oskan-Clarke and Adelle Tracey - into the semis, Tracey impressing with a new personal best of 2.00.28.