The pregnant Duchess of Sussex is cutting back on her busy commitments during the second week of the royal couple's tour of Australia and the Pacific, it was announced Sunday.

Meghan has already left Prince Harry to do some tour appointments on his own, such as climbing the Sydney Harbour Bridge.

On Sunday morning, she did not join him in watching the Invictus Games cycling events; Harry was overheard saying to a competitor that she was resting.

But Meghan did join Harry for an official lunch with Prime Minister Scott Morrison at the Royal Botanical Gardens, and in the afternoon joined Harry on the harbour to watch sailing.

Harry was dressed casually in a grey jacket and blue shirt, while Meghan sported a black turtleneck jumper by Australian company Wolford, tight black jeans by Outland and a blazer by L'agence.

Meghan has mentioned jet lag a couple of times during the couple's busy schedule. Last week at Bondi Beach, she told a well-wisher that she had been up at 4:30 am doing yoga.

Kensington Palace announced that Meghan will not take part in Monday's official engagements with Harry for their visit to Fraser Island in Queensland, but instead will rest privately.

The royal couple were due to meet indigenous elders and rangers to learn about the island's history, but moving around the island can be difficult as it is mostly sand.

Kensington Palace confirmed that the couple will visit Fiji and Tonga during the week before returning to Sydney for the weekend. They then fly on to New Zealand.

"After a busy program, the duke and duchess have decided to cut back the duchess' schedule slightly for the next couple of days, ahead of the final week-and-a-half of the tour," the palace announced.

Meghan was with Harry at the opening of the Invictus Games at the forecourt of the Opera House on Saturday night, which was delayed an hour due to a sudden wild electrical storm.