The 2012 Bank of America Chicago Marathon felt different than recent years because the temperatures were noticably chillier and Liliya Shobukova didn't win.
Rita Jeptoo, of Kenya, and Atseda Baysa, of Ethiopia, were neck and neck coming into the finish line for a thrilling photo finish. Baysa broke the tape at the finish line miliseconds ahead of Jeptoo.
Shobukova, who finished third, failed to become the first runner -- male or female -- to fourpeat. The Russian distance runner had to pull out of the 2012 London Olympics with stomach cramps and has also been bothered this year with a leg injury.
"My legs weren't quite doing what I wanted to do," she said through a translator. "I feel good (now). Fourth time is a goal, a challenge for every athlete and I'm going to try to do it. My first (Chicago) marathon in 2010 was also cold. And I won."
American Tatyana McFadden, who won three gold medals at the recent London Paralympic games, defends her women's wheelchair crown. Canadian Josh Cassidy, fourth last year and 2012 Boston Marathon champ, is the top men's wheelchair contender.
Most of Chicago's previous races have run under seasonal conditions expected on Sunday. But there have been temperature extremes. In 2007, temperatures hit 88 degrees under high humidity and organizers shut down the race early. One runner died and 49 were hospitalized.
Last year, temperatures reached the high 70s, the fourth time in five years with unusually warm conditions. A 35-year-old North Carolina firefighter, running to raise money for a charity, collapsed and died 500 yards from the finish line. Autopsy results were inconclusive.
The Chicago Marathon is among five races in the World Marathon Majors, a two-year cycle of races with a $1 million purse split between the top male and female point earners. Boston, New York, Berlin and London marathons also make up the field.