Nairobi - Kenya's reigning athletics world champions face a tough challenge from a crop of young runners as the country prepares to choose the team to defend their title in London.
Athletes will gather in Nairobi on Friday and Saturday for national trials ahead of the August world athletics championships, two years after Kenya's victory in Beijing with 16 medals, including seven golds.
While Kenya's track team has been known to peak for the big occasion, as evidenced in Beijing, a shake-up among the team, race fatigue and ongoing concerns over doping will loom large over the trials.
Reigning world champions Ezekiel Kemboi, Asbel Kiprop and David Rudisha are hoping to make the team, but have struggled to hold up against a new crop of Kenyan runners this season.
"The season is only two-and-a-half months old but from the results we have seen so far we are likely to be seeing a transitional change in Kenyan athletics," says veteran athletics journalist Peter Njenga.
"Kemboi has won the world title for four consecutive years, and from the way he ran at the Rome Diamond League, finishing 17th, shows he's past his prime.
"Rudisha, likewise, at 28 is not growing younger either. He has had his time and he is struggling to get back to his old form" said Njenga.
Rudisha, the two-time 800m world and Olympic champion had asked to be exempted from competing at the trials and qualify on a wildcard, but his request was turned down by Athletics Kenya, and he is set to compete in Friday's first semi-final against his old rival, Ferguson Rotich.
The race will also feature two teenagers - Kipyegon Bett and Willy Tarbei - who scored stunning victories in the Shanghai Diamond League and at the Racers Grand Prix in Jamaica in May and early June.
Tarbei, a former 800m World Under-18 champion and regular training mate of Rudisha, handed the world record-holder his second defeat of the season at the Usain Bolt invitational meeting in Kingston on June 11.
Kenyan athletes remain on the watchlist by the World Anti-Doping Agency (WADA), which means the runners have come under a lot of scrutiny from Athletics Kenya (AK) and the International Federations of Athletics Federations.
Top athletes, including javelin world champion Julius Yego have complained that the authorities are paying too much attention to the issue of doping at the expense of the athletes' training programmes.
But AK chief Jackson Tuwei warned that the athletes seeking selection to the world championships must meet several requirements, including attending anti-doping seminars organised by the Kenya Anti-Doping Agency..
"We are not yet out of the woods on this issue of doping. Therefore the seminars are not optional. There are important conditions required for each athlete to meet before the entries to the world championships in London," Tuwei said.
"Each athlete is required to be tested three times before taking part in the world championships."