By Mark Butler
BBC Sport's athletics statistician
Imagine if Britain's 93rd-ranked tennis player won Wimbledon. Well, something along those lines happened last year at the Commonwealth Games.
John Kelai won marathon gold in Delhi despite being that far down on Kenya's list of marathon runners in 2010. Such a statistic shows how much the balance of power in marathon running has shifted during the history of the London Marathon.
At the time of the first race 30 years ago, there were no Kenyan men or Ethiopian women in their respective top 100s. Nowadays those two countries have a majority share in the rankings and I can't recall a significant marathon which is not dominated by runners from these nations.
Ethiopia's Kebede is tipped to retain his London Marathon title
Of 42 elite marathon races last autumn, 38 were won by Kenyan men and the other four by Ethiopians. Ever longer lists are required to show significant numbers of those from outside East Africa.
Britain haven't had a man in the world top 100 since 2007 and only Mara Yamauchi made the women's list last year. But rather than moan about British standards, let's marvel at the strength in depth from East Africa.
At the prestigious Berlin Half Marathon earlier this month, there was further evidence of the quickening flow of talent from that part of the world. Both races were won by Kenyan juniors who were internationally unknown a year ago.
It's quite possible that those vying for gold on the streets of London in August 2012 will include Kenyans or Ethiopians whose names are not currently known outside of their countries.
For London 2011, Ethiopian Tsegaye Kebede would be a good bet to retain his men's title, but it is Kenya who have flooded the market in elite male marathoners with over half of the world top 100 every year starting in 2005.
Among women the picture is different because Ethiopia are now leading the way with a sharp improvement over the past two years. We'll see evidence of this on Sunday as the women's elite field include five Ethiopians, all in their twenties.
Four of them are already among their country's all-time top 10 in their event and the other - Aberu Kebede - won last year's Berlin Marathon by a full minute.
Such has been the turnover that the list no longer includes the greatest-ever African woman runner, Derartu Tulu, who, incidentally, was the last Ethiopian woman to win at London, 10 years ago.
It's only a matter of time before another world-beater emerges from their expanding pyramid of talent.
Ethiopian All-Time Top 10
1 2:20:42 Berhane Adere 2006
2 2:21:31 Askale Tafa* 2008
3 2:21:34 Gete Wami 2006
4 2:21:52 Berhane Adere 2006
5 2:22:04 Atsede Baysa* 2010
6 2:22:38 Aselefech Mergia* 2010
7 2:22:44 Beyenne Tsegaye 2010
8 2:23:06 Merima Hasen 2010
9 2:23:09 Bezunesh Bekele* 2008
10 2:23:21 Fatuma Roba 1998
* Entered for 2011 London Marathon