Grand Sonata secured a thrilling victory in the $1,995,000 Kentucky Turf Cup Stakes (G2T) at Kentucky Downs on September 7, following a race plan that unfolded perfectly. Trainer Todd Pletcher's assistant, Amelia Green, noted that after a series of tough trips, the plan to keep Grand Sonata near the rail worked flawlessly. Jockey Tyler Gaffalione executed this strategy by settling the horse off the pace early and finding an opening at the quarter pole, allowing Grand Sonata to surge forward and claim victory with a track-record time of 2:24.93.

Grand Sonata's win came after a disappointing performance in the Sword Dancer Stakes (G1T) at Saratoga, where a slow pace contributed to his last-place finish. In the Turf Cup, however, the defending champion, Get Smokin, set a favorable pace, giving Grand Sonata the setup he needed. Despite a late challenge from Highway Robber, Grand Sonata held on to win by a half-length, with Tawny Port finishing third and the favored Integration in fourth.

This victory earned Grand Sonata a fees-paid berth to the Breeders' Cup Turf (G1T) at Del Mar on November 2, though Green mentioned that a decision on whether to compete there would be made later. The win also marked a personal achievement for Gaffalione, who had finished third or fourth in the Turf Cup for the past four years. Grand Sonata, a homebred for Whisper Hill Farm, became the fourth graded stakes winner of the season for his sire, Medaglia d'Oro, and improved his career record to 5-6-2 from 23 starts with earnings of over $2 million.