The Wallabies have lost former captains James Horwill, David Pocock and Will Genia to injury, leading Deans to call upon the services of a player who retired from domestic rugby at the end of the Super 15 season.
Sharpe was only part of the current Wallaby squad after a second-row injury crisis saw him persuaded to postpone his international retirement until later this year yet the 34-year-old is suddenly carrying the hopes of nation once more.
With 108 Test caps to his name and more than a decade of international service, Sharpe offers a level of experience no other Wallaby can match and Deans believes that will be vital as the Lions' next opponents look to back up last week's win over South Africa.
"Sharpey has just been immense for us this year," said Deans, after bringing Nick Phipps, Pat McCabe and Kane Douglas into his starting line up and switching Berrick Barnes to full back.
"It's well deserved. He's been superb.
"When you look at the profile of the group at the moment, we've lost a lot of experience so he's become even more important for us."
Sharpe played against the Lions for the Reds back in 2001 and, even though he intends to call time on his stellar career at the end of the Rugby Championship or after the Bledisloe Cup encounter with New Zealand in October, it wouldn't be a major surprise if he stayed around for the visit of the 2013 tourists.
For now the Force stalwart is focused on ensuring the Wallabies build on their 26-19 success against the Springboks, even if the Gold Coast native does admit he'll be a particularly proud man come Saturday night in Robina.
"To have the privilege of leading Australia in the first ever Test to be played on the Gold Coast is an experience I will always treasure," said Sharpe, who captained his country in two previous Test matches in 2004 and 2005.
"It's rare when you have played at this level for as long as I have to come across something totally new, but to play a Test in my home town is something I would never have imagined happening.
"No one else in the squad has played Argentina before but I have and they will be tough, incredibly passionate and uncompromising. You only have to look at what they have achieved to date in their tournament matches to see what a threat they will be.
"It's important we keep our focus as a team, build on what we achieved last weekend in Perth, and add to that momentum."