Shalane Flanagan has announced she will race the Berlin Marathon on September 28, shooting for a sub-2:20 finish time and the American record.

After notching her current personal best of 2:22:02 in Boston earlier this year, Flanagan needs to better Deena Kastor's time of 2:19:36 from the 2006 London Marathon to claim the record.

Last month, Flanagan opted out of the 10,000 meters at the USATF Championships to focus on her fall marathon training. She placed first at the Rock 'n' Roll Chicago Half Marathon on July 20, running 1:09:45, and will compete at Saturday's Beach to Beacon 10K in Maine.    

"We think Berlin is one of the fastest, if not the fastest, courses," Flanagan told the Oregonian. "There were too many variables with Chicago, and you would be gambling with the weather."

Flanagan's fastest marathon on a record-eligible course is the 2:25:38 she ran in Houston to win the 2012 Olympic Marathon Trials.