Scott Sio signed a deal with the Wallabies and Brumbies until at least the end of 2022.
Exeter Chiefs wrapped up top spot in the Premiership by beating Northampton Saints, which sealed a top-four berth regardless after Harlequins' narrow loss at Wasps.
Newcastle Falcons suffered relegation from the Premiership with defeat at Gloucester, while Saracens dismantled Exeter Chiefs at the other end of the table.
Harlequins missed out on the opportunity to move back into the Premiership play-off places as it lost to table-topping Exeter Chiefs.
Exeter Chiefs have broken Saracens' all-time Premiership record by scoring a try in 72 consecutive matches.
Saracens scored a last-gasp try to deny bottom club Newcastle Falcons a losing bonus point at Allianz Park.
Sergio Aguero struck twice, while Vincent Kompany, Fernandinho and Gabriel Jesus were also on target as Manchester City thumped Watford 5-0.