BERLIN — Not content to cover 26.2 miles in a neat loop, Patrick Makau of Kenya turned the Berlin Marathon into his own personal conga line Sunday while setting a world record of 2 hours 3 minutes 38 seconds.  Just before Mile 17, Makau swung from one side of the flat course to the other, once, twice, three times, then surged. This zigzagging tactic exposed and dropped the previous record holder, Haile Gebrselassie of Ethiopia, who had run 2:03:59 in Berlin in 2008.  The race kept growing more futile for Gebrselassie, who did not finish. He stopped briefly after Makau’s swerving and then again for good just before 22 miles, experiencing a surprise and debilitating flare-up of exercise-induced asthma, his agent said.  Gebrselassie also dropped out of the New York City Marathon after 16 miles last November, citing a knee problem. He briefly retired, then reconsidered, but will again be forced to confront his athletic mortality.  While Makau, 26, became an early men’s favorite at the 2012 London Olympics, Gebrselassie’s stirring international career — considered by many the greatest ever — appears to have reached irreversible decline. At 38, he seems to have set his last world record and surrendered to emerging runners who might soon cover the marathon under 2:03. That time would have been unthinkable a decade ago.  “A new generation is coming that is running very well,” said Makau, who averaged 4:43 per mile and shaved 70 seconds off his previous best of 2:04:48, which was run at the 2010 Rotterdam Marathon.  Not all of the older generation is ready to concede, though. Paula Radcliffe of England, 37, the women’s world-record holder, ran her first marathon in nearly 23 months Sunday after giving birth to her second child and easily qualified for the London Games with a third-place finish in 2:23:46.  In a Kenyan sweep, Florence Kiplagat won the women’s race in 2:19:44 and became half of what may be the world’s best marathoning couple. In April at the Boston Marathon, her husband Moses Mosop (2:03:06) and fellow Kenyan Geoffrey Mutai (2:03:02) both ran faster than Makau’s Berlin time. But the Boston race does not qualify for a world record because of its elevation drop and its failure to meet international requirements for a loop course.  In the Berlin men’s race, six pacemakers formed a V-shaped formation, leading a pack of five elite runners as if they were migrating geese. They stayed on record pace the entire race, with the lead group going through halfway in 1:01:43. By 16.7 miles, the pacemakers were down to two for the only remaining contenders, Makau and Gebrselassie.  Makau then veered from one side of the road to the other three times, with Gebrselassie drafting a step behind him. He thought it might confuse Gebrselassie and also tire him. It did.  “He was trying to use me to maintain the pace,” Makau said. “I decided not to carry anybody.”  Makau then stepped on the accelerator and Gebrselassie could not respond.  “He knew that Gebrselassie was a front runner,” said Makau’s agent, Luis Posso. “Once there was some space, he couldn’t catch up.”  Gebrselassie slowed, then stepped off the course, put his hand on his stomach and bent over, struggling to breathe. He has experienced exercise-induced asthma during his career but not in recent months. In fact, he did not use his inhaler Sunday, said Jos Hermens, Gebrselassie’s agent.  “Maybe he should have taken it,” Hermens said.  Less than a minute later, desperately needing a fast time to preserve any chance at making the Ethiopian Olympic marathon team, Gebrselassie jumped back into the race. One pacemaker, then another, eventually drifted back to assist him, but he stopped again, unable to breathe sufficiently enough to hold his pace. He will probably look to run the Dubai Marathon in January seeking qualification for his fifth Olympics, Hermens said.  “It’s the end of an era, but not the end of Haile,” Hermens said.  By 20 miles, the last pacemaker dropped away, like the booster stage of a rocket. Makau blazed ahead on his own for the final 6.2 miles. In April, he had fallen at the London Marathon but recovered to finish third in 2:05:45. There was no such accident Sunday as Makau ran unimpeded, arms swinging wide, repeatedly blowing his nose, drawing away with a muscular style that made him the fastest marathoner in history.  He might have run a second or two faster, but Makau had to jump over a small advertising placard in his final strides to align himself with the tape at the finish line. One of the pacemakers, Stephen Kwelio Chemlany of Kenya, hung on for second place in 2:07:55, four minutes behind the winner.  “This has been the greatest day of my running life,” Makau said. “When I woke up, my body didn’t feel very good. As the race went on, I felt better. At 25 kilometers (15.5 miles), I felt I could break the world record. It’s a great thing to beat Haile, one of my heroes.”  And, he added later, it was great to beat an Ethiopian, especially one who has set 27 world records, has twice won Olympic gold medals at 10,000 meters and has been a primary challenger to Kenya’s primacy in East African distance running.  “Everyone in Kenya is very happy,” Makau said.  Meanwhile, Gebrselassie was left to consider a career inevitably muted by age. Even for an athlete as remarkable as he has been, there are only a finite number of great races in a runner’s legs.  “Whatever happens, he’s always going to be looked at as probably the greatest male distance runner the world has ever seen,” Radcliffe said of Gebrselassie. “I hope he doesn’t retire, but he’s achieved so much. After some point, you have to say, ‘My body’s probably done with it.’ ”  This article has been revised to reflect the following correction:  An earlier version of this article misstated Patrick Makau's age as 25.  An earlier version of this article misstated Patrick Makau's age as 25.
Patrick Makau won with a time of 2:03:38, topping the previous record held by Haile Gebrselassie of Ethiopia.