Qipco have offered to increase the prize-money of the one-mile showpiece on August 1 from £300,000 to seven figures, in a bid to attract the two unbeaten stars of international Flat racing.
With a total of 28 victories from 28 runs between them, Frankel and Black Caviar are officially the two highest-rated horses in the world.
In 2011, the Henry Cecil-trained Frankel established himself as the best horse on the planet with a series of scintillating performances, including the 2000 Guineas, the Queen Elizabeth II Stakes and the Sussex itself.
He is scheduled to start his four-year-old campaign in the JLT Lockinge Stakes over a mile at Newbury on May 19, before possibly stepping up to a mile and a quarter later in the summer.
Cecil said earlier in the week: “After that (Lockinge), he’ll tell me what to do and everything is open. There’s Ascot and the Prince of Wales’s or the Queen Anne, going a mile in the Sussex Stakes, or the Eclipse and the Juddmonte.”
Meanwhile, in an unbeaten run stretching to 19 races, Black Caviar, trained by Peter Moody, is the darling of Australian racing and is due to be campaigned in Europe this summer, with the six-furlong Golden Jubilee Stakes at Royal Ascot an intended target.
She has run over seven furlongs once, on her penultimate start, but never over a mile in her career so far.