Great Britain's world number one Oliver Townend on Sunday retained his lead in equestrian eventing at the Tokyo Olympics, keeping a clean sheet on the cross-country course, while reigning Olympic champion Michael Jung from Germany fell back to a disappointing 10th place.

After completing two of the three disciplines making up eventing, also known as horse triathlon, Great Britain is on course for team gold, with Australia in the silver medal position and France in bronze.

After dressage and cross-country, the show jumping on Monday also will decide whether Germany's Julia Krajewski can retain her individual silver medal position and Great Britain's Laura Collett can hold onto bronze.

Jung, who bagged individual gold at Rio 2016 and London 2012, celebrated his 39th birthday on Saturday by coming first in the dressage test discipline, was penalized after knocking down an obstacle in the cross-country event, a 4.4-km (2.7-mile) course dotted with 36 fences, dropoffs and ponds to negotiate at speeds of around 34 km per hour (21 mph).

Equestrian sports do not differentiate between athletes and horses on the basis of gender or sex, and athletes over the age of 50 often win medals.

Thailand's Arinadtha Chavatanont crashed into a water feature after her horse slipped when landing on a small piece of land between the obstacle and the pond. Both rider and horse were fine, but it spelled the end of the country's dreams of a medal for its first-ever team in the sport.

Sweden's Therese Viklund was also eliminated after she fell off her one-eyed horse Viscera, her airbag vest inflating to cushion her fall.