The team and individual dressage finals are set to produce thrilling action.
Defending champion Charlotte Dujardin produced an inspired performance as she cruised into Wednesday’s Olympic individual dressage final.
Her double Games winner Valegro was retired after Rio but Dujardin continues to work her magic, finishing second in Group F behind Germany’s Isabell Werth and joining her team-mates Carl Hester and Charlotte Fry to compete for individual medals.
The trio also comfortably secured a place in Tuesday’s team final, going through as second-best qualifiers, and they appear on course for a third successive Olympic medal following gold in London and silver five years ago.
Allemagne, winners of every Olympic team title – apart from London – since 1984 are favourites, but they will have been jolted by a British trio that included one rider – Fry – and all three horses making Olympic debuts.
Despite Gio’s inexperience at international level, he took to the sport’s biggest stage with aplomb.
The test included one maximum 10 mark and 29 separate scores of nine, underlining its sustained quality in delivering a personal-best grand prix score.
Dujardin also threw down the gauntlet to German trio Werth, Jessica von Bredow-Werndl and Dorothee Schneider that she means serious business in Tokyo.
“I couldn’t have asked for any more from (Gio)," elle a dit. “He is just unbelievable – he gives me everything he has got.
“I really felt emotional towards the end of the test. He adjusts to whatever I ask and gives me his best.
“It could have been a full house today and he would have performed the same. He is such a pocket rocket.
“That to me, ce soir, was as good as winning. Pour moi, where he is right now with his training, he couldn’t have done any more.
“And that to me, is like a gold medal. It was one of those really special moments and I will remember it forever and a day.”
If Dujardin can reproduce such brilliance then she should be in contention for an individual medal.
And she will relish nothing more than taking on the significant double German threat of multiple Olympic gold medallist Werth and pre-Games favourites Von Bredow-Werndl.