Pippa Middleton and her younger brother James have started their charity cycle ride across the US.
The high-society girl and famous sibling of the Duchess of Cambridge, née Kate Middleton, donned her patriotic kit and cycling shorts for the gruelling Race Across America.
The challenge will see Pippa and her seven male teammates make the 3,000 mile journey from San Diego, California to Annapolis, Maryland in an estimated eight days.
CLICK ON PHOTOS FOR GALLERY
Pippa Middleton started the challenge in California
Setting off on Saturday, Pippa, James and the eager team were spotted mounting their bikes at Oceanside Pier. The brunette beauty looked effortlessly cool in her blue, reflective sunglasses and at the top of her game as she cycled alongside her brother.
While sporty Pippa, 30, is used to putting her fitness to the test and has participated in various charity races in the past, the high-endurance ride is set to be a challenge for even the most accomplished cyclists. Less than 200 individuals have completed the race in its 32-year-history.
Pippa, who has raised nearly £4,000 for charity, wrote on her JustGiving fundraising page that the team were planning to pedal between 350 and 500 miles a day.
Pippa Middleton is hoping to complete the ride in eight days
Riders are expected to cycle for five to six hours at a stretch and take 25-minute breaks, with parts of the route crossing the Arizona desert and including climbs of more than 170,000 feet.
As for sleeping arrangements, the author admitted that she wasn't fazed about being the only female in the team's motor home. "Everyone will sleep when and where they can," she told The Mail On Sunday.
Pippa Middleton and James Middleton start pedalling
Earlier this week Pippa was announced as the newest ambassador for the British Heart Foundation.
The athletic columnist is cycling in aid of the heart charity as well as The Michael Matthews Foundation, which was set up following the death of young adventurer Michael, who passed away while descending Mount Everest in 1999.
Michael's brother James, a close family friend of the Middletons, is also taking part in the race.
Following the challenge, Pippa and the team will head over to Istanbul to take on the Bosphorus Cross-Continental Race – the 6.5km historical swim between Europe and Asia.