Athletics:Yusuf Saad Kamel was a surprise winner of the 1,500 metres after his explosive sprint finish saw him clinch gold - but there was no medal for favourite Asbel Kiprop.
In a slow, cagey race, the Kenyan-born athlete, now representing Bahrain, positioned himself well heading into the home straight and kicked hard to overtake Ethiopia' Deresse Mekonnen, who had attempted to seize the initiative at the bell, and crossed the line in 3 minutes 35.93 seconds.
Olympic silver medallist Kiprop got his tactics all wrong, leaving himself with far too much to do having opted to sit back behind the pack for much of the race and ended up finishing fourth despite being heavily tipped for gold.
The champion of two years ago, Bernard Lagat of America, looked as though he was slipping well down the field around the final bend but found extra reserves in the last 50m to snatch the bronze.
Kenya's other medal hope Augustine Choge - the world leader this year - faded into fifth place.
Kamel's achievement sees him follow in the footsteps of his father Billy Konchellah, who won two golds over 800m in 1987 and 1991.
Emily Freeman easily advanced to the semi-finals of the women's 200 metres.
The British sprinter produced a confident display to finish second in her quarter-final behind Jamaica's Veronica Campbell-Brown in a time of 23.10 seconds.
Campbell-Brown, the Olympic champion, is bidding for her first world title over this distance having been a distant silver medallist back in 2007 when Allyson Felix romped to a stunning triumph.
Felix also coasted into the semis as she casually went through the motions in clocking 22.88 to take first place in her heat while fellow Americans Muna Lee, ChaRonda Williams and Marshevet Hooker progressed.
Germany's Robert Harting produced a final throw of 69.43 metres to win a thrilling discus competition and send the home crowd in Berlin wild.
The 24-year-old - a silver medallist in 2007 - looked as though he'd have to settle for second place again when Poland's Piotr Malachowski, who had been leading from the first round, produced a national record of 69.15 in the fifth round to extend his advantage over the field.
But Harting sparked wild scenes at the Olympic Stadium when unleashing a stunning personal best at the death and when Malachowski could only send his sixth throw out to 67.33, the celebrations could begin.
Defending champion Gerd Kanter of Estonia - also the Olympic gold medallist - had to settle for bronze with 66.88m.
Harting marked his triumph in style by ripping off his shirt before grabbing hold of Berlin mascot - a huge bear - and holding it upside down, much to the delight of the fans.