Kastor runs 1:11:38 to set new U.S. 40-and-older mark.
The 41-year-old Kastor won last year's event in 1:13:25, and was victorious at the Rock 'n' Roll Dallas Half two weeks ago.
Hundreds of kids took part in the Junior Carlsbad kids races on Saturday morning!
Kastor, 41, ran her fastest half marathon since 2011.
Deena Kastor will chase Masters records at Sunday’s Rock ‘n’ Roll Dallas Half Marathon.
The Olympian was forced to withdraw from the Rock ‘n’ Roll New Orleans Half Marathon with the flu.
The club will be renamed the ASICS Mammoth Track Club.
The 40-year-old will be gunning for an American Masters record this weekend.
Take a look back at the exciting 2013 season and see who we named the top runners of the year.
Mary Cain announced last week that she was turning professional.