In the final, Campbell will face New Zealand's Olympic bronze medallist Mahe Drysdale, after he destroyed Belgium's Tim Maeyens, who was less than two seconds behind him in the Beijing final.
"It's going to be harder and I'm going to have to find something from somewhere," said Campbell of taking on the man he beat in the final in 2007.
"He had an easier race, will be fresher and is in fantastic form so it will be more of a case of me going out to beat him."
Campbell has chosen not to race in the final World Cup regatta next weekend, saving himself for the World Championships in August, but Hodge and Reed look set to face New Zealand again in Lucerne.
The British pair, racing for their clubs Leander and Molesey, had a slightly faster start but the longest distance they led by was three feet.
The duo have experimented this week with switching Reed into the stroke seat but they were unable to raise their rate to hold onto the Kiwis as they steadily moved clear.
Campbell made it through to the single scull final at Henley
"We have started off the last few days very confident but this race was an immense battle," said Reed.
"We were aggressive with our rate and very speedy whilst moving freely but the Kiwis were just faster than us.
"We need to change our finish, which will be a tall order."
A young GB men's quadruple scull will face the Polish Olympic champions after a close, half-length victory over a Californian crew.
And the new GB women's quad face a tough challenge against their New Zealand counterparts after battling to a two-length win over the NZ lightweight crew in the semi-finals.
Great Britain's men's coxless four of Matt Langridge, Alex Gregory, Richard Egington and Alex Partridge went straight through to the final after their American opponents withdrew.
They will face New Zealand's lightweight crew, who rowed down an Italian heavyweight four before the latter hit the wooden booms that line the course late in their race.
The GB men's eight have a straight final against a US eight on Sunday in Henley's blue riband event, the Grand Challenge Cup.
The British women's eight beat their own squad's Under-23 crew and will take on Yale University on Sunday.
And Olympic bronze medallists Matthew Wells and Steve Rowbotham beat a double sculls combination from Sichuan, China by a length and three quarters to book a place against Kiwis Matthew Trott and Nathan Cohen in the final.
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