Natasha Baker won Great Britain's first equestrian gold medal of the 2012 Paralympic Games at Greenwich Park.
The 22-year-old, who is making her Paralympic debut, triumphed in the Grade II individual championship.
Baker, from Uxbridge in Middlesex, built superbly on her success at last year's European Championships, when she took the individual and freestyle titles.
She scored a Paralympic Grade II record 76.857% on Cabral to claim the title, but only after a powerful twin German challenge fell just short.
Defending Paralympic champion Britta Napel posted 76.048% for second on Aquilina 3, with Angelika Trabert and Ariva-Avanti (76.000%) third.
Despite an early draw in the 23-rider competition, Baker delivered a calm and controlled performance, sparking what is expected to be a Games gold rush for the dressage quintet of Baker, Lee Pearson, Sophie Wells, Deb Criddle and Sophie Christiansen.
Pearson contests the Grade Ib individual event on Saturday afternoon, when victory would give him a 10th Paralympic gold medal of his stellar career.