The 28-year-old Briton kicked in the last mile to earn the victory.
The 33-year-old is hoping to become the first American to ever win the Beach To Beacon 10K.
The 33-year-old has her eyes on Deena Kastor's 2:19:36 mark.
Over 20,000 entrants took to the streets of The Windy City on Sunday morning.
Shalane Flanagan and Andy Wacker won the 2014 Rock 'n' Roll Chicago Half Marathon.
Runners had the chance to meet America's best female marathoner before Rock 'n' Roll Chicago.
The 33-year-old is aiming for a sub-2:20 marathon clocking this fall.
America's top marathoner will lead the 5K on July 19 and race the half marathon on July 20.
There’s a reason Olympic runners have coaches—the same reason you may need one.