It has become a cliché in sport for competitors to describe a poor performance as a bad day at the office but, for Haile Gebrselassie, it means what it says. Running gets Gebrselassie out of the office. A bad day at his desk is if his real estate business, or his construction company, or the schools he has built, or his hotel interests, give him grief.

Gebrselassie has taken to business with the same vigour that helped him to 16 world records, two Olympic and four world 10,000 metres gold medals, and three world indoor titles during a track career from which he retired two years ago. In the offices of Haile & Alem International plc, in Addis Ababa, he and his wife each have two secretaries. For seven hours a day, Gebrselassie wears a suit.

Yet, despite his growing commercial empire, it is business as usual for Gebrselassie the runner. On Sunday, he will line up in the Flora London Marathon, still a contender, aged 34. Up at 5.45 each morning, he trains before and after work. His victory in the Berlin Marathon last September, in the fastest time of 2006, proves that he can still cut it. Not only does he still have big goals — to win the London Marathon, to break the world record, to win the Olympic gold medal in Beijing next year — but he wants to turn back the clock and come out of retirement from track racing. He said yesterday that, while he would not run the marathon at the World Championships in Osaka, Japan, this summer, the 10,000 metres was an option.

And there’s more. The 2012 London Olympics is on Gebrselassie’s radar. “I have no plan to stop running,” he said. “By 2012 I will be 39,” he added, noting how Mamo Wolde and Miruts Yifter, fellow Ethiopians, had won Olympic medals in their forties. “I can be a very good track runner still but my problem is potential injury problems if I do speed work for the track.”

Gebrselassie was forced to leave the track after persistent Achilles tendon trouble and set about conquering the marathon. “When I was preparing for 5,000 and 10,000 metres I had a lot of injuries but, since I started the marathon, I have had no major problem, maybe because I have not been doing speed work,” Gebrselassie said.

When Gebrselassie finished ninth in the London Marathon last year, he blamed the incompatability of his running style with the wet surface. Still running on his toes, the relative lack of contact between his foot and the ground caused him to slip, he said. Since then he has been working on a flatter foot action, although, ironically, the weather on Sunday is predicted to be warm and dry.

Too warm, at a forecast 20C (70F), for a world record, the leading contenders said yesterday. Gebrselassie, Paul Tergat, the world record holder, from Kenya, and Stefano Baldini, the Olympic champion, from Italy, opined that the weather, and a likely tactical race, would combine to keep the winning time short of the world record.

“There are too many champions in the race for a world record,” Baldini said. “Nobody will want to work for the other guy’s benefit.” Tergat’s world record of 2hr 4min 55sec has survived since his victory four years ago in Berlin, the course on which Gebrselassie set his career-best time of 2:05.56 seven months ago.

Such is the status of the London Marathon that Gebrselassie said to win it in a world record time would be as great a thrill as winning the Olympic title at the distance. The fact he has not won London in two attempts, yet has triumphed in his other three — Berlin, Am-sterdam and Fukuoka — makes it all the more alluring.

For Tergat, it is four goes at London and counting. Although he has won in Berlin and New York, Tergat has had to settle for two runners-up finishes. Tergat won five consecutive World Cross Country titles, and four global 10,000 metres silver medals behind Gebrselassie, before turning to the marathon. On Sunday the two race for the first time since 2002. A business reunion.