PHOTOS: Roger Federer lights up inaugural AO Ceremony, partners Andre Agassi & Ash Barty

The Happy Slam debuted an Opening Ceremony on Saturday that leads into the start of its main draws.

And what a sight it was.

The headline act, of course, was previously announced to be Roger Federer. For the first time in six years, the six-time Australian Open champion stepped out on Rod Laver Arena for an unforgettable evening with some of his most beloved colleagues in the "Battle of the World No.1s".

📲🖥️ Stream a replay of the AO Opening Ceremony on the Tennis Channel App!

Federer, who didn't get to compete Down Under in his final two active years on tour due to injury, played doubles alongside Andre Agassi. With Aussie legends Pat Rafter and Lleyton Hewitt across the net, the exhibition later included a surprise substitution when three-time major winner and home hero Ashleigh Barty replaced Agassi.

A gallery of highlights from a night full of nostalgia: