London - Former Australia captain James Horwill will skipper Harlequins during the 2017/18 season, the English Premiership side announced on Monday.
"I'm very humbled and honoured to be asked to captain such a great club, it's certainly something that I won't be taking lightly," said 32-year-old lock Horwill in a statement issued by the London club.
"The hard work for us as a squad starts now and we want to make Harlequins as successful as it can be."
Quins finished sixth in the 12-strong Premiership last season and so missed out on a place in the top four title-deciding play-offs despite the side boasting several current and ex-internationals.
"The exciting thing is, we haven't reached our potential," added Horwill, capped 62 times by the Wallabies.
"We have played well in parts, but we have more to give, both in an individual capacity, and as a group."
Horwill succeeds scrumhalf Danny Care who, in common with another former Harlequins captain Chris Robshaw, has often found himself away from the team for large parts of the season because of his England commitments.
Care, appointed Quins captain two years ago, led the Twickenham Stoop-based side to the 2015 European Challenge Cup final and was in charge on the field when they secured a place in the elite European Champions Cup for this first time in three years.
"Since Conor (O'Shea, the former Harlequins director of rugby but now the coach of Italy appointed me, it has been a huge honour to captain the club," Care said.
"It's a hard job in itself, but it is made harder when you're away with international commitments for so long, which is why I felt someone who is around all the time should do the job.
"I, alongside the rest of the squad, will fully support James in his new role. He is a fantastic leader and the right man to take the club forward."
Horwill joined Harlequins from the Reds, a side he played for over 100 times and captained to the 2011 Super Rugby title, in 2015.
He has made 40 appearances for Harlequins, scoring five tries.
Horwill captained Australia on 16 occasions, including during the Wallabies' 2013 series loss to the British and Irish Lions.