Prince William and his wife Kate are guests in the Royal Box at Wimbledon to watch Andy Murray play Richard Gasquet on Centre Court.
Rumours they may even be joined by Kate’s sister, Pippa Middleton, were later dismissed.
They will watch the fourth seed play Frenchman Gasquet, the 17th seed, in the fourth round during stifling conditions.
The duchess is known to be a keen tennis fan. The pair were greeted by enthusiastic applause and a standing ovation as they took their seats.
They will also watch the reigning men's champion Rafael Nadal, the no 1 seed, play Juan Martin Del Potro, of Argentina. Venus Williams is also due to play on Centre Court.
The Duchess’s appearance comes ahead of her first official Royal Tour to America later this week.
An increased police presence was visible around the grounds and a Metropolitan Police helicopter patrolled for hours before their arrival.
It is their first time in the Royal Box together.
In a break from recent poor weather, the mercury is expected to climb towards 100F this afternoon.
Conditions are however, due to turn later this afternoon, with forecasters predicting thunderstorms.
A Clarence House spokesman said the Royal couple were visiting Wimbledon in "a private capacity".
Murray said he would not be nervous playing his Centre Court match in front of the Duke and Duchess of Cambridge.
"It's great for tennis to have people like that coming to watch," he said.
He added of the Duchess : "She has attended Wimbledon in the past and is a long-time fan of tennis."
Other guests in the Royal Box include the Duchess of Gloucester, Princess Michael of Kent, David Bernstein, the chairman of the Football Association and Sir Mervyn King, the Governor of the Bank of England.
Billie Jean King, the American 12-time grand slam tennis champion, including Wimbledon five times, and Mark Webber, the Australian Formula 1 driver, and his wife Ann Neal are also due to appear in the Royal Box.
Tim Henman's parents Anthony and Jane are also Royal Box guests today.
William and Kate, who married in April, are long standing tennis fans.
Kate has visited the championships twice before.
In 2007 she attended with a friend to watch Rafael Nadal play Swede Robin Soderling on Court one and in 2008 she visited again.
Last week a letter was displayed at the 125th Championships which the Duchess wrote to tennis bosses thanking them for their hospitality.
In it she thanked them for finding Centre Court tickets for her and assuring her some peace and quiet.
As the royal box guests arrived today thousands of sun drenched fans applauded.
But the heartiest welcome was reserved for the royal couple who were given a standing ovation.
Kate wore a light cream, triple-tier knee-length dress and William wore a dark blue suit with a rose coloured tie.
The retractable roof was partially covered to shade the royals' end of the arena.