New Delhi: A keen contest awaits in the seventh edition of the Airtel Delhi Half Marathon as top athletes across the world gear up for the challenge in absence of two-time winner and course record holder Deriba Merga of Ethiopia.

Merga, ranked fourth in the world and winner of titles here in 2008 and 2009, pulled out of the annual event at the last moment due to an injury.

The absence of Ethiopian, who holds the course record of 59.15 min set in 2008, leaves an open field with the onus shifting on to last year's runner-up Lelisa Desisa to hold the country's flag high.

Lelisa, who lost out by a fraction to Kenyan Geoffrey Mutai last year, will be supported by Tilahun Regassa.

The Kenyan challenge, on the other hand, will be spearheaded by Sammy Kitwara in the absence of Mutai.

Kitwara, the fastest athlete in the men's field with a personal best of 58.48 set in September this year, has already made his intentions clear saying he will be looking at a sub-60 finish.

"I don't want to commit anything now, it will depend on the route as well. There are some ups in the route besides some sharp corners. But I want to give it my best shot," said Kitwara.

The athlete had, however, earlier said ,"59 min is just playing the game."

The other strong Kenyans in the field include Stephen Kibiwott, with a personal best of 59.37, Philemon Limo, Mark Kiptoo and Emmanuel Bett.

In the women's section, defending champion Aselefech Mergia of Ethiopia will look to replicate her previous performance, however, she is set to get some tough competition from Kenya's Lucy Wangui Kabuu, who made a comeback to the international arena after a hiatus of three years earlier this September.

Kabuu is the fastest in the field this year with a personal best of 67.06 clocked at the North great Run in the UK on her return.

The athlete looks confident ahead of Sunday's run and will be gunning for the world record set by her fellow contrymate Mary Keitany (1:05:50) in February this year at Ras Al Khaimah, United Arab Emirates.

Kabuu will be backed up strongly by Lydia Cheromei, Doris Changeywo and the young Valentine Kipketer.

Mergia, meanwhile, will be supported by strong women's field, which includes fellow Ethiopians Merima Mohammed, runners-up last year and former world half marathon silver medalist Aberu Kebede.

On the national front, Irappa D Akki will spearhead the challenge in the men's section while Lalita Babbar will lead the contingent in the women's section.

Besides Akki, the men's field will also have names like Santosh Kumar, runner-up for the last two years, BC Tilak, winner of the half marathon in the Mumbai Marathon 2011, Deepchand Saharan, the Indian course record holder with a timing of 1.04.00, Satish Kumar, Soji Mathew, Lyngkhoi Bining, Ratti Ram Saini and Angad Kumar, to name a few.

Irappa had clocked 1:4.32 while winning last year and is confident of bettering that mark this year and having a shot at Deepchand's course record.

The strong women's field will have last year's runners-up Kiran Tiwari, besides Asian Games medallists Kavita Raut and Sudha Singh.

Raut, with the fastest time of 1:17.12 clocked while winning in 2008, missed out on the last two editions and will be looking to make an impact when she takes the starter's flag.

Sudha Singh, who, according to Indian elite athletes coordinator Sunita Godara, is in fine form and will be looking to better her timing of 1:17.39 she had clocked in 2008.