All three leaders will be anxious not to slip-up in the debate, but face a difficult task discussing the extent of spending cuts needed to tackle Britain's deficit without scaring off voters who were finacially bruised by the recession.
Dr Andrew Hilton, director of the Centre for the Study of Financial Innovation, told Al Jazeera that the parties have very different plans to get out of the financial black hole.
"There's no consensus. Do you cut hard and fast, or do you wait as long as you can?" he said.
"The UK economy is not in great shape and its quite possible we could kick the UK back into recession if we get this wrong. The situation is very serious in the UK."
Brown goes into the debate in the knowledge that his performance could make or break his hopes of clinging to power.
He has endured a torrid 24 hours after being recorded deriding a pensioner who questioned him on immigration as a "bigoted woman".
The story has dominated the media in the run-up to the debate.
The US-style leaders' debates have proven hugely influential in the campaign so far.
The Liberal Democrats have surged in the polls following strong performances from Clegg.
After decades of being regarded as a minor force in British politics, the party is now consistantly coming second in opinion polls, forcing Labour back into third position.
With just a week left in the race for Downing Street, polls suggest the country is headed for a hung parliament, where no clear winner emerges.