One of the country's youngest MPs has been named as shadow chancellor in Tory leader Michael Howard's reshuffle of his frontbench team.
Osborne: To shadow Gordon Brown
George Osborne, 33, long seen as one of the party's rising stars, will now face Gordon Brown in the Commons.
Dr Liam Fox, who was chairman, becomes shadow foreign secretary. Francis Maude becomes party chairman and David Cameron, 38, takes on education.
Former Cabinet minister Sir Malcolm Rifkind is work and pensions spokesman.
The ex-foreign secretary, who has been out of the Commons for eight years, will shadow Work and Pensions Secretary David Blunkett.
The reshuffle follows Mr Howard's decision to step down as Tory leader - and all the contenders for his job have been given weighty briefs.
Former Tory deputy prime minister Michael Heseltine told BBC News: "I think it's a very dramatic re-shuffle, it's putting all the talent in the front line. It makes a nonsense of the suggestion that Michael [Howard] should go."
Mr Howard should stay in his job for 18 months, he added.
Earlier this week shadow environment minister Tim Yeo and shadow defence minister Nicholas Soames both resigned.
Education spokesman Tim Collins lost his seat at the general election.
Mr Osborne will be staring across the Despatch Box at Gordon Brown, who in his eight years as chancellor has already seen off Tory hopefuls including Oliver Letwin, Michael Howard, Michael Portillo and Francis Maude.
Oxford-educated Mr Osborne said apart from holding Mr Brown to account, his bigger job was to help broaden the appeal of the Conservative party through his economic policies.
"There's a lot of work to be done," he told BBC Radio 4's PM programme.
Other key appointments include Michael Ancram switching from shadow foreign secretary to defence, replacing Mr Soames.
David Willetts, moves from work and pensions to shadow the new government department of productivity, energy and industry.
David Davis remains shadow home secretary, while former shadow chancellor Oliver Letwin takes on the environment, food and rural affairs portfolio.
Theresa May stays as shadow secretary of state for the family and will also take on the culture, media and sport brief.
Shadow chancellor - George Osborne
Shadow chief secretary to the Treasury - Philip Hammond
Shadow foreign secretary - Liam Fox
Education - David Cameron
Work and pensions - Sir Malcolm Rifkind
Defence - Michael Ancram
Shadow home secretary - David Davis
Rural affairs - Oliver Letwin
Northern Ireland - David Lidington
Chief whip - David Maclean
Family - Theresa May
Health - Andrew Lansley
Constitutional affairs - Oliver Heald
Transport - Alan Duncan
Shadow Commons leader - Chris Grayling
International development - Andrew Mitchell
Deregulation - John Redwood
Local and devolved government - Caroline Spelman
John Redwood will remain as spokesman on deregulation and Alan Duncan is named as transport spokesman.
Sir Malcolm, 58, told BBC News 24 he was "absolutely delighted" with his new brief because pensions were one of the "greatest challenges" facing the country over the next few years.
"I will be looking at David Blunkett across the Despatch Box and holding him to account on behalf of the country," he said.
Sir Malcolm said Mr Howard had appointed a "very strong team" which includes "people of experience and vitality".
"I think it is going to be a formidable alternative to the current government," he said.
Sir Malcolm refused to say whether he would be throwing his hat into the leadership ring, adding that pensions were sufficiently important that he did not need other distractions.
Dr Fox described the new shadow cabinet as "a collection of the best talents in the party".
"I look and see a lot of fresh faces, a lot of energy there and I think that the Labour party are going to face a re-invigorated and re-energised opposition," he told BBC News 24.
Lib Dem parliamentary chairman Matthew Taylor accused the Tories of failing to be a serious alternative government.
"The faces may change, but their policies remain out of touch with the majority of the British people."