The couple had a busy Saturday, starting off with the opening of an extension to the Anzac memorial in Hyde Park, then on to Cockatoo Island to watch the Jaguar Land Rover Driving Challenge as part of Invictus.
Thomas, who still has not met Prince Harry in person, also praised Markle for her performance in Australia for her first major worldwide tour as a member of the royal family.
Prince Harry's gracious speech at the Invictus Games opening ceremony on Saturday night managed to move the nation and the world as he gushed about wife Meghan Markle and their future baby.
A Royal source told ABC News that "she's feeling fine but resting".
The source continued: "She sat through breakfast with a smile on her face, but Harry looked a bit uncomfortable". We have to make sure she is well-paced and not overdoing it.
The Duchess of Sussex during a visit to Taronga Zoo in Sydney on the first day of the Royal couple's visit to Australia, Oct.16, 2018.
It is one of the more official events of the Royal tour, which is the first official overseas trip for the Royals as a married couple.
Now before I close, I want to say something directly to our hosts, the people of Australia.