To heighten the drama, Didier Pasquette, a Frenchman, and Jade Kindar- Martin, an American, plan to perform the feat without a safety net. Asked what will happen if they lose their footing, Pasquette says: "If we fall, we die."
The two men are tackling one of the widest parts of the river, the 1,200ft between the Oxo Tower on the South Bank and HMS Wellington, moored on the Victoria Embankment.
At sunset, to the accompaniment of fireworks and techno music, they will step on to a steel wire strung between cranes stationed on opposite banks and inch along, aided only by balancing poles.
If all goes well, they will meet midway and pause to drink a glass of champagne before embarking on the trickiest manoeuvre of all: brushing past one another to continue across.
Pasquette, 29, and Kindar-Martin, 23, members of a French acrobatic troupe, have been rehearsing for weeks on a high wire erected in a cornfield in northern France. The crossing, which is expected to draw thousands of spectators and is intended to publicise the 1999 Thames Festival, is one of their most dangerous stunts to date.
Pasquette - who strode across a wire suspended between the twin towers of Wembley Stadium in 1991 - said yesterday that he had banished from his mind all thoughts of falling. "This is the longest tightrope walk I've ever done, and I have to confess that it's a little bit scary."
Kindar-Martin preferred to dwell on the pleasures of his chosen metier. "It's the way that I express myself, it's how I communicate," he said. "Dancers dance, artists paint, and I do this. It's an adventure. I step on to that wire and I step into another world. I exist only for that."Reuse content