Usain Bolt\u2019s final appearance on the track ended in agony on Saturday as he pulled up injured running the final leg of the World Championships 4/100 metres relay as Great Britain beat the United States for a shock gold medal. Bolt, who had to settle for bronze in the individual 100 metres, had been hoping to sign off from the sport by leading Jamaica to a fifth successive relay gold but there were already struggling in third when he collected the baton.Runners blamed pre-race delays that kept them waiting too long.\u201cInside (the stadium) it was cool. We keep on warming up we get in there. That\u2019s our true friend, that\u2019s Usain, that\u2019s our training partner. I felt it. To see the legend on the ground, struggling; our champion must come out, must finish like that,\u201d said Jamaican sprinter Yohan Blake.\u201cWe were in the stadium a little bit too along with our clothes off, you know. I understand that it\u2019s TV time, it\u2019s TV magic but I think that we could have took our clothes off a little later and I think that\u2019s where it came from, the cramp,\u201d added Justin Gatlin from the US team which took the silver medal.Mo Farah\u2019s aura of invincibility after six years of unrelenting success was finally cracked in his very last major track race as he lost his world 5,000 metres title to Ethiopia\u2019s Muktar Edris. Seeking a fitting end to his matchless long-distance racing career before moving to marathon running, the 34-year-old Briton\u2019s bid for a fifth straight global 10,000/5,000 metre double was scuppered as he had to settle for the silver. He was philosophical about the outcome.\u201cIt\u2019s been an amazing night. It\u2019s been an incredible support, the home crowd has been amazing. I\u2019m sad. I\u2019m disappointed not to win to come out\u2026 it would have been nice to win. But in athletics everything, anything is possible. And today a better man won on the day and there\u2019s nothing I could have done. I did my best. I tried my best. The Ethiopians had a game plan and they figured out a way to beat me and it worked.\u201dBritain also took silver in the women\u2019s sprint relay, as individual champion Tori Bowie anchored the United States to victory in the women\u2019s 4\u00d7100 metres relay.Australia\u2019s Sally Pearson completed one of the great sporting comebacks when she overcame two years of injury to win the world 100 metres hurdles title at the age of 30. Previously a world and Olympic gold medallist, she held off Dawn Harper Nelson, one of four Americans in the field, for an emotional triumph.Maria Lasitskene became the first Russian to win a gold medal at the World Championships after successfully defending her high jump title. The 24-year-old, competing as an authorized neutral athlete, stretched her unbeaten streak to 25 competitions by clearing 2.03 metres to triumph in the London Stadium.Frenchman Kevin Mayer led throughout the day to win the men\u2019s decathlon title, despite surviving a scare in the pole vault. The Olympic silver medallist successfully came through the javelin and 1,500 metres to see himself safely home after two exhausting days.