Ascot's director of communications Nick Smith says he expects 25,000 people to attend the inaugural British Champions Day at the course on Saturday.
The day sees five championship races including the Queen Elizabeth II Stakes featuring Frankel and the Champions Stakes involving Opinion Poll.
The meeting is being called the richest fixture in British racing with £3m in prize money on offer on Saturday.
"The demand is unprecedented," Smith told BBC Radio Berkshire.
Smith added: "We are very pleased with how sales have gone so far, our premier admissions tickets sold out two weeks ago.
"It is a new event so it is great that the event is catching everyone's imagination.
"I think we are looking at a crowd of 25,000 which is well in excess of the 18-20,000 we used to get for the QEII a few weeks earlier but it is what you would expect for what is now undoubtedly the best race day this year."
The demand for the event compares to that of Royal Ascot in the summer, although Smith expects the crowd to be very different.
"It is a completely different kettle of fish to Royal Ascot," said Smith.
"Royal Ascot is in the middle of the summer and has been in people's diaries for years and years. We get a lot of people who come to Royal Ascot who aren't necessarily racing or sports fans but this is a day for people who really know their sport and really love their racing."
"30,000 is actually our capacity out of the big summer events because we don't have the big outdoor marquees so a 25,000 crowd in a capacity of 30,000 is a tremendous figure for year one."
The appearance of Frankel is undoubtedly the highlight of the day, although all five championship races feature some of the biggest trainers, jockeys and horses from across the world or racing.
And former trainer Ian Balding has urged people not to miss Saturday's action.
"It is fantastic, it is the most valuable day of racing ever in this country," Balding said.
"Frankel is extraordinarily good and just wins his races by long distances and is what they call a monster."