Kirui has struggled with injuries, but is hoping to return to the top and represent Kenya at Worlds next year by running sub-2:05 in Chicago.
Kirui is still dreaming of not only making the Kenyan Olympic squad, but winning marathon gold to add to his 2012 silver. He'll start 2016 with the Tokyo Marathon in February.
They lead a slew of other 2:04-2:06 men. Olympic champion Tiki Gelana heads the women's race against Flomena Cheyech (2:22:44) and Commonwealth Games 10,000 champ Joyce Chepkirui.
33-year-old Kirui has struggled in recent years with a stress fracture in 2013 and DNF at Boston 2015, but thinks he's in shape to challenge his 2:05:04 PR from 2009.
Kirui: “It (the injury in 2013) taught me that I have to listen to my body. At that time, I was a crazy runner!"
2013 champ Lelisa Desisa and former world record holder Patrick Makau (2:03:38 PR) are the headliners, but there's depth behind them with five sub-2:05 men overall and five more sub-2:07 + HM world record holder Zersenay Tadese (58:23).