Prince William made a surprise visit to the Australian Open to watch world No 1 Roger Federer yesterday and the Swiss star turned on the style.

After touring communities near Melbourne affected by bushfires last year that killed 173 people, William arrived at the Rod Laver Arena in time to see the 15-time Grand Slam champion demolish Romanian Victor Hanescu 6-2, 6-3, 6-2.

The crowd gave William a warm ovation as he took his seat with Tennis Australia officials and he applauded enthusiastically as Federer marched into the third round.

After the game, Federer was interviewed courtside by former Grand Slam champion Jim Courier, who asked the Swiss great to officially welcome royalty to Melbourne Park.

Federer, turning to face the laughing William, duly obliged.

"Your Royal Highness. Welcome to the world of tennis," he said. "Thank you for coming."

William earlier told a Melbourne reception that being in Australia was the realization of a long-held dream. He recalled his much-loved late mother Princess Diana's affection for Australia and the "profound impression" it made on her.