The British crew, comprising Redgrave, Matthew Pinsent, Tim Foster and James Cracknell, won their semi-final in emphatic style.
On a crisp but sunny morning at Penrith Lakes, they surged into the lead from the start and were more than a length up before the halfway mark, leaving Slovenia and the United States trailing in their wake.
It gave the Brits the opportunity to cruise the second half of the course, taking it easy to conserve energy for the bigger effort to come on Saturday.
Central lane
It also means they will have a central lane in the final, which is considered to be the most advantageous.
"It was a solid row, not spectacular at all, but we won and you can't ask for more than that.
"There are still four boats who could win the event. But if we row our best we know we can win it.
"I don't know if the other boats think they can win it or not."
Cracknell added that the quartet were relishing being in the unusual position of underdogs: "At the World Championships we've been favourites and winning has almost been a relief.
"Coming to Sydney, that's not been the case. Having been beaten, we're not favourites. We're the fourth seeds. I've really enjoyed the last eight weeks, tracking someone down rather than always being hunted."
Britain's big rivals Australia also qualified in a thrilling race in the other semi, getting the nod in a photo-finish with Italy in a time half a second faster than the cruising Brits. New Zealand were the other crew to qualify.
At halfway, Britain were 2.51 seconds ahead of the field with Slovenia a surprise second and they always looked comfortable as they came home to cross the line in 6:02.28.
The Slovenians produced the fastest sprint for the line, coming home 1.79 seconds behind Britain with USA taking the third final spot.
Surprise casualties were France, World Championship finalists last year and silver medallists in Atlanta, who now race in the B final.
Related to this story:
Wish good luck to Redgrave and the boys
(21 Sep 00 | Sports Talk)