Kristine Lilly scored 10 minutes into the second half as the host Boston Breakers held on for 2-1 victory over the Sol, which suffered its first loss.
Brittany Bock scored for the Sol (3-1-1) in the 63rd minute.
Boston (3-2-0) took a 1-0 lead two minutes in on a goal by Kelly Smith.
The teams play next Sunday at the Home Depot Center.
