The quest for Olympic ticket will inspire New York marathon champion Mary Keitany of Kenya in her bid to hit two birds with one stone in London marathon on Sunday.

Keitany, 33, is returning to London confident a win will secure her a ticket in the Kenya team to the Rio Olympics and also tag her as favourite to win gold in the games in her second attempt.

However, she faces stiff challenge from compatriots Florence Kiplagat, Priscah Jeptoo and Jemima Jelagat Sumgong.

Only the best three will claim the ticket though Boston marathon bronze medallist Joyce Chepkirui has an outside chance of being considered too.

"I have done my training well and am ready for the assignment in London. It is always great to see the support and crowds along the streets of London, but it is all about myself and what I have done that gives me confidence, I will weather the storm," said Keitany as she jetted out to London.

Keitany will be out to show that she' s the "real deal" and even the race coordinator Dave Bedford believes she will be the woman to beat.

Keitany ran the fourth fastest time on record when she won the London title for a second time in 2012 and returned last year to place second behind Ethiopia' s surprise winner, Tigist Tufa.

She retained her New York City Marathon title in November last year and was crowned the Series winner of the World Marathon Majors earlier this year.

The African record holder is ready to join the elite trio of Ingrid Kristiansen, Katrin Dorre and Paula Radcliffe as a three-time London winner.

"Mary Keitany is probably the classiest person in this field," said Bedford as he cast his eye over the women' s line-up he' s put together for this year' s 36th event.

"She was the favourite for the Olympic marathon in London in 2012 and only finished fourth, but subsequently found out she was pregnant. She took some time out and now she' s back," Bedford said.