Australia international James Horwill has signed a new deal with Aviva Premiership side Harlequins, keeping him at Twickenham Stoop until 2020.
The 31-year-old lock, who has been capped 62 times, captained the Wallabies at the 2011 World Cup.
He joined Harlequins from Super Rugby franchise Queensland Reds in 2015 and has since gone on to make 33 appearances for the club.
"From the moment James joined 18 months ago, he has shown himself to be both a world-class player and an outstanding leader," said Harlequins director of rugby James Kingston.
"His infectious enthusiasm and drive illustrates exactly why he captained Australia on 16 occasions and he has proved a shining example to the rest of the squad."
Horwill has scored one try in 11 games this season, helping Harlequins to their current sixth position in the Premiership, 15 points behind leaders and defending champions Saracens.
"In extending his contract to the summer of 2020, he has crucially committed himself long term," added Kingston.
"This signing is a statement of our intent for the coming years."