Haile Gebrselassie will join the elite line-up for the Flora London Marathon on 17 April subject to a fitness test. The Ethiopian, who had Achilles surgery after the Athens Olympics, will run a half marathon at the end of the month and then make his decision.
Race director David Bedford said: "We hope he comes through the half-marathon test with flying colours."
If he runs, Gebrselassie will face a high-quality field including arch rival Paul Tergat, the world record-holder.
His decision to opt for London if fit is bad news for the Boston Marathon, whose organisers were hoping the 33-year-old would take part in their race on 18 April.
He finished third in the 2002 London Marathon, in only his second race over the distance.