He was a star of arguably the greatest night of sporting drama the United Kingdom has ever seen, but four-time Olympic champion Sir Mo Farah is in danger of ending his career frustrated and beaten by the years. Farah ran his first track 10,000m in Birmingham on Saturday night since winning the 2017 world title, and it was a sad sight to see him trail home in eighth place, a massive 22 seconds shy of the qualification time needed to book his place to Tokyo. The Briton, whose first Olympic gold came in the same magic spell as Jess Ennis in the heptathlon and Greg Rutherford in the long-jump in 45 minutes of golden carnage at London 2012, partly blamed a foot injury for the poor performance, saying it had prevented him training over the previous fortnight. It's clear, however, that while Farah has spent the past three-and-half years attempting to replicate his track success in the marathon - and failing - life has moved on. Farah's time was certainly well short of the 27 mins 28 secs needed to qualify for the Games, which are due to start on July 23. More decisively, Joshua Cheptegei, who finished second to Farah in 2017, has succeeded him as world champion and, in October, the Ugandan broke Kenenisa Bekele's 15-year-old world record. His time was more than 35 seconds quicker than Farah could manage at his best. For 38-year-old Farah, an athlete who conquered the world, it must have been devastating. Certainly a long way from the halcyon 'Mobot' days nine years ago that so enthralled London. He has another three weeks to make the qualifying time, but is it the end of the road? It's something that puzzles sports fans the world over. Why do athletes who have proved themselves superhuman, the best of all, continue until they are no longer competitive at the top table? Surely better to call it quits at the top, rather than watch younger, faster, stronger rivals power past? The list is endless. To name but a few; Seb Coe, Linford Christie, Carl Lewis in athletics; George Foreman, Evander Holyfield, Muhammad Ali and Mike Tyson in boxing, Gary Neville, Ronaldinho, Wayne Rooney in football ... All great names, but all with one thing in common: they should have retired earlier. Perhaps that's what sets them apart in the first place, that burning ambition to succeed no matter what the obstacles. It can only be hoped that Farah, a legend up there with every one of these names, does not regret his last hurrah.