Horwill stripped of Australia captaincy for England match
James Horwill watches a training session at Suncorp Stadium in Brisbane on September 6, 2013
Wallabies coach Ewen McKenzie opted to have No 8 Ben Mowen lead the side instead for the opening match of Australia's European tour.
McKenzie said Horwill hadn't been at "peak form" of late but, with fellow lock Rob Simmons ruled out after re-aggravating a knee injury during Tuesday's training session, he nevertheless retained his place in Australia's second row.
Meanwhile one-time 'bad boy' fly-half Quade Cooper was named as vice-captain by former Australia prop McKenzie.
"There's no doubting James is a world-class leader but it's important he is putting his own personal performance first and playing to the level we know he is capable of on a weekly basis," McKenzie said.
"By his own lofty standards, James would admit he hasn't been at peak form. So, we've made the decision to this week remove the added pressures and responsibilities of being a captain so that he can focus entirely on bringing his 'A' game," explained McKenzie, who inherited Horwill as captain when he replaced former coach Robbie Deans following Australia's 2-1 series loss to the British and Irish Lions in July.
This will be the second time Mowen has captained the Wallabies, having led them to a narrow 14-13 victory over Argentina in Perth last month when Horwill was injured -- one of just two wins Australia have achieved during McKenzie's seven games in charge.
A year ago Cooper was dropped from the Wallaby set-up after saying Deans had created a "toxic environment" and never played another Test for the rest of the New Zealander's time in charge of Australia.
But McKenzie knows Cooper well, having coached him at Queensland.
And the Australia boss said he's no qualms about his leadership changes, with Cooper replacing half-back partner Will Genia as vice-captain.
"Ben now gets another opportunity to lead his country, while we're recognising Quade for the ongoing decision-making role he plays on the field and the positive involvement he continues to make in contributing to the culture of the team off the field.
"However, like we do every week, we'll re-assess all selection decisions for next week's game against Italy after we focus on taking care of business against England on Saturday night," McKenzie added.
McKenzie's comments about Cooper also appeared to be a thinly-veiled reference to his recent decision to axe gifted back James O'Connor, now with English Premiership side London Irish, following several embarrassing off-field incidents.
Australia have made four changes from the side that lost 41-33 to New Zealand in Dunedin earlier this month.
Sitaleki Timani partners Horwill in the second row, with a reshuffled backrow seeing Mowen move to No.8 following the return of Scott Fardy at blindside flanker while Nick Cummins returns on the wing.
Australia have won just three out of 10 Tests so far in 2013 but have won eight of their last 12 matches against England and three of their last four at Twickenham.
Their latest victory over England came in the last Anglo-Australian clash, at Twickenham in 2012, where Cummins's maiden Test try helped the Wallabies to a 20-14 win.
Israel Folau; Adam Ashley-Cooper, Tevita Kuridrani, Matt Toomua, Nick Cummims; Quade Cooper, Will Genia; Ben Mowen (capt), Michael Hooper, Scott Fardy; James Horwill, Sitaleki Timani; Ben Alexander, Stephen Moore, James Slipper
Replacements: Saia Fainga'a, Benn Robinson, Sekope Kepu, Kane Douglas, Ben McCalman, Nic White, Christian Leali'ifano, Bernard Foley