The Kellyn Gorder-trained daughter of Tiznow won by 2 1/2 lengths for owners Sandra Sexton and Brandi Nicholson.
The Martha Washington is a Road to the Kentucky Oaks points race, awarding points on a 10-4-2-1 scale to the first four finishers toward a start in the Longines Kentucky Oaks (G1).
In Saturday's one-mile test for 3-year-old fillies, Red Ruby rated in fourth behind Secret Passion, who had the early lead and took the field of five through a quarter-mile in :23.77. Sassy Sienna took over as Secret Passion began to fade and Red Ruby started making her way forward between rivals as a half-mile went in :47.87.
As six furlongs went in 1:12.63, Red Ruby made a move around the far turn in the three path and cut into Sassy Sienna's lead at the top of the stretch. With some urging from jockey Robby Albarado, Red Ruby ran past that rival and drew clear to win in a final time of 1:39.67 over the sloppy, sealed track.
The lightly raced winner entered the Martha Washington off a 3 1/2-length maiden score in a 1 1/16-mile event at Churchill Downs in November. The filly finished second in her only other start, a one-mile maiden special weight at Churchill in October. With two wins, she's earned $123,000.