Former Wallaby Giteau returns to rugby at age 41

"We are over the moon to secure Matt's services for the upcoming season," San Diego coach Danny Lee said in a statement on Wednesday.

"He is a world-class player who will bring an incredible wealth of knowledge, a competitive attitude, and a drive to succeed with him that will no doubt spread throughout the squad."

The 103-test Wallaby played at three World Cups and had a key role in Australia's run to the 2015 final in England.

He also won seven elite competition trophies across the globe in his two-decade career, including titles in Australia, France, Japan and the US in 2021 with the short-lived Giltinis.