Sophie was all cheers for her niece Zara Tindall.
Zara has competed at the Cornbury House Horse Trials in Oxfordshire and her aunt is singing praises for her.
The 60-year-old duchess took time out of her busy schedule to support her niece, just 24 hours after returning from a five-day trip to Canada.
The Duchess of Edinburgh's appearance at Cornbury House came shortly after she met with King Charles at Clarence House, where they had talks just as Prince Harry was about to set down for "a private tea" with his father.
The duchess had recently returned from Alberta, Canada, where she attended the Spruce Meadows Masters Tournament and carried out engagements focused on British-Canadian links and charity work.
While cheering on Zara, Sophie wore a sophisticated outfit, pairing a patterned grey jacket with a crisp white shirt and a flowing navy skirt.
She also perched a pair of sunglasses on her head, anticipating the sun interrupting her view of the events. Zara, a former Olympic equestrian, participated in the competition, navigating the Oxfordshire course with ease.
Zara's daughter, Mia, 11, was seen closely monitoring the technical aspects of the performances, sharing in her mother's and grandmother's passion for sporting in the saddle.