By Sports Reporter/DohaWorld 800 metres champion Mohamed Aman of Ethiopia is the latest star to join the field of the IDL Doha 2014, the kick-off of the 14-meeting IAAF Diamond League series on Friday.Aman, who raced to world championships gold in Moscow last summer, successfully defended his world indoor 800m title in Sopot, Poland two months ago. The Ethiopian record holder is the last man to have beaten world record holder and Olympic champion David Rudisha, who was forced to withdraw from Friday’s race due to injury.Aman is the latest name to join the invasion that overwhelms Doha every May.It’s a friendly incursion, one in which the leading roles are played by Kenyan and Ethiopian middle and long distance forces who either simply come and dominate an event on their own or settle their rivalry scores on the track of the Qatar Sports Club.First, the rivalry. This year it’ll likely be at its most apparent in the women’s 3,000 metres where Genzebe Dibaba will set out to continue a break-out year in which she’s already set two world records.The 23-year-old Ethiopian shattered world indoor standards at both 1,500 and 3,000 metres in February; in the latter with a performance the world hasn’t seen in more than two decades, indoors or out.In Doha, her primary challenge will come from Kenya, led by 2013 world championships 5,000-metre silver medallist Mercy Cherono, and backed up by Viola Kibiwot, who crossed the line fourth in the same Moscow race. Dibaba meanwhile will have support from Almaz Ayana, who raced to bronze in the Moscow 5,000.But let’s not overlook the 800 metres where despite world record holder David Rudisha’s withdrawal, Kenya still arrives with a world champion --in the women’s race.Eunice Sum produced one of the bigger surprises at last year’s world championships when she out-raced and out-maneuvered the heavily favoured Olympic champion Mariya Savinova on her home turf. Here she’ll race against a woman who taught her a thing or two: Janeth Jepkosgei, a world championship gold, silver and bronze medallist in 2007, 2009 and 2011.In the men’s race, Kenya will be well represented by Job Kinyor (1:43.76 PB, 2nd in Doha in 2012) and Ferguson Cheruiyot (1:43.22, 2013) but they’ll come up against the stiffest of tests in Aman, who improved to 1:42.37 in Brussels last year.On the men’s side, with no longer race on the programme this year, the east African rivalry will show most clearly in the 1,500 metres where despite Kenyan dominance of the event in Doha, a serious challenge can emerge. The Kenyan attack is about as fierce as it gets. There is reigning world champion and 2008 Olympic gold medallist Asbel Kiprop, Nixon Chepseba and Silas Kiplagat, the 2011 world silver medallist, who have taken top honours in Doha the last three seasons. They’ll take on Aman Wote, the 2014 world indoor silver medallist, and Mekonnen Gebremedhin of Ethiopia, who raced to 2012 world indoor bronze and finished sixth at the 2012 Olympic Games.Then there is the sheer dominance that the world has come to expect by Kenya in the 3,000-metre steeplechase. Consider the numbers of the top three in Friday’s race:• There is Ezekiel Kemboi, the 2004 and 2012 Olympic champion, winner of world titles in 2009, 2011 and 2013, with silver medal finishes in 2003, 2005 and 2007.• There is Brimin Kipruto, the 2008 Olympic champion, 2007 world champion, 2004 Olympic silver medallist, and 2011 world silver medallist. In Monaco in 2011, he clocked 7:53.64, just 0.01 shy of the world record to become the second fastest in history.• And then there is steeplechase journeyman Paul Kipsiele Koech, the meet record holder and at 7:54.31 the third fastest men ever in the event.