George Osborne will face Labour's Angela Eagle for the first time at Prime Minister's Questions on Wednesday, giving him a further chance to burnish his leadership credentials.
David Cameron is away visiting EU leadership as part of his ongoing efforts to convince his counterparts to reform Britain's membership of the EU.
Mr Cameron appointed Mr Osborne as First Secretary of State in May, allowing him to deputise at Prime Minister's Questions and suggesting the Chancellor is his preference to succeed him at Number 10 when he steps down at the end of the decade.
Mr Osborne will face a tough task on Wednesday opposite the combative Commons performer Angela Eagle, the Shadow First Secretary of State and Shadow Business Secretary.
She is seen as a key link between Jeremy Corbyn and the moderate wing of the Labour party and much attention will be focussed on whether she follows her leader's approach of asking crowd-sourced questions.
It will be the second time Mr Osborne will take Prime Minister's Questions - in the summer he deputised for Mr Cameron as he took on Shadow Foreign Secretary Hilary Benn.
During the five years of Coalition Nick Clegg took charge when the Prime Minister was away, while William Hague deputised during a special session when all three main party leaders visited Scotland a week before the independence referendum.
Mr Osborne's hopes of becoming Tory leader were dashed last month after a poll showed Boris Johnson and Theresa May ahead of the Chancellor among Conservative supporters.
It found that Mr Johnson is the favourite candidate for leader among a third of Conservative supporters, a quarter back Ms May, while the number of Tories who prefer Mr Osborne has slumped to 23 per cent, slipping from first to third in the space of six weeks.
