NAIROBI, Kenya, August 12- Olympic champions Brimin Kipruto and Nancy Langat will headline Kenya’s challenge at this weekend’s IAAF London Grand Prix.

Lagat who is currently having the season of her life hopes to notch up her third straight win in three weeks with victory in the women’s 1500m on Friday with the main challenge coming from Ethiopia’s Genzebe Dibaba.

Kipruto leads a stellar cast of Kenyans in the men’s 3000m steeplechase in which they are expected to dominate.

Michael Kipyego, Paul Koech and Linus Chumba should also set the Crystal Palace Stadium alight with world class middle distance running.

Speaking of world class, a scrap of titanic proportions is expected in the women’s 5000m final where an all star line up will be battling for reputation.

World and African champion Vivian Cheruiyot will have to do more than reenact her thrilling win in the African Athletics Championships over Ethiopian counterpart Meseret Defar.

Add in Tirunesh Dibaba, Linet Masai and World Junior Silver medalist Mercy Cherono, Cheruiyot will have to dig deep to show that she is the undisputed queen of the 5000m.

Janeth Jepkosgei hopes to put her Africa Championships disappointment behind her when she lines up in the women’s 800m race.

Jepkosgei who tried to come to her terms with her defeat in Nairobi will be up against home favourite home favourite and European bronze medalist Jenny Meadows.

Meanwhile, Tyson Gay will look to follow up his victory over world and Olympic champion Usain Bolt in Stockholm last week when he goes head to head with Asafa Powell in the 100 metres.

American sprinter Gay handed Bolt only his second professional 100m defeat when easily beating the Jamaican in last Friday’s Diamond League meet in the Swedish capital, clocking 9.84 seconds.

Bolt on Tuesday announced he would not be competing for the rest of 2010 because of a back injury, leaving sprint rivals Gay and Powell to battle it out in the three remaining Diamond League meetings.

Powell, who like compatriot Bolt has run a world-best time of 9.82 secs this year, was absent in Stockholm owing to back trouble and admits he is not at peak fitness.

"I have had a lot of problems with my groin and that spread to my back and hamstrings," Powell said. "Since Paris (July 16), I have been unable to train at 100 percent. I have been getting treatment twice a day every day and slowly I am getting better.

"My coach (Stephen Francis) and manager (Paul Doyle) have all my races lined up but I am not even aware of what is next," added Powell. "All I am doing is focusing on getting healthy and back able to race. I am taking it day by day."

Gay, a three-time world champion, has beaten Powell over 100m on English soil already this season – at the Diamond League event in Gateshead last month – and will be the favourite at Crystal Palace after his recent exploits against Bolt.