Shady Sabrina, an 8-year-old mare, remained undefeated this year in Maine to win the $25,000 final of the Mid-Summer Classic Pacing Series — the feature race on Scarborough Downs’ day of celebrating its 60th anniversary Saturday. Driven by Kevin Switzer, Shady Sabrina took control early and took advantage of a slow pace to hold off all challengers. The winning time was 1:54.3.