Chumba won the men’s race last year in 2 hours 09min 25sec, while Kiplagat took the women’s crown in 2:23:33.

A personal best of 2:04:32 makes the 29-year-old Chumba the fastest in this year’s field, but he is expected to face strong competition from Ethiopia’s Tsegaye Kebede who won this race in 2012 with a personal best of 2:04:38 and finished second in 2010.

Only three other men in the field have run 2:07:00 or faster, including Chumba’s fellow Kenyans Abel Kirui and Micah Kogo.

Kirui, a two-time world champion, finished just two positions and 32 seconds behind third-placed Chumba in Tokyo in February.

Kogo, who set his personal best of 2:06:56 when finishing fourth in Chicago in 2013, placed fourth in Paris earlier this year in 2:08:03 - the second-fastest time of his career.

Also lining-up is Ethiopia’s Abayneh Ayele, who placed fourth at the International Association of Athletics Federations (IAAF) World Half Marathon Championships in Cardiff in March, finishing just behind Britain’s four-time Olympic gold medallist Mo Farah.

World record holder Dennis Kimetto was initially scheduled to race but the Kenyan, who clocked 2:02:57 in Berlin in 2014 and a Chicago course record of 2:03:45 in 2013, was forced to withdraw due to a leg injury.

In the women’s race at the World Marathon Major, Kiplagat will aim to become the first female to win consecutive titles since Ethiopia’s Berhane Adere triumphed in 2006 and 2007.

The 29-year-old, who holds the half marathon world record of 1:05:09, heads the field with her 2:19:44 from Berlin in 2011.

Fellow Kenyan Edna Kiplagat, who is the only other woman in the field to have run faster than 2:20:00, will be making her debut in Chicago.

As well as a third-place finish in Tokyo earlier this year, the 2011 and 2013 world champion set a 10 kilometres personal best of 31:06 in June.

Ethiopia’s Atsede Baysa is the other former victor in the field having won in 2010 and 2012, the latter in her personal best of 2:22:03.