SYDNEY - WITH a newly-tuned piano at hand and a borrowed kitten for company, Pope Benedict XVI was recovering from jet-lag in Australia ahead of World Youth Day celebrations.

As the pontiff rested at a Catholic retreat in Sydney on Monday after his 20-hour flight from Rome on Sunday, Christian icons and hundreds of thousands of Catholics converged on Australia's most populous city.

'This morning, he would have had early morning mass at the Kenthurst Chapel and then he's got time for quiet prayer and he'll be resting up, he'll be taking a good sleep,' said World Youth Day spokesman Danny Casey.

The piano at the Opus Dei study centre in the north-western Sydney suburb of Kenthurst had been specially tuned ahead of the piano-playing pontiff's visit, Mr Casey said.

And he confirmed that organisers had borrowed a kitten to keep the cat-loving Pope company.

'We wanted to make it a genuine house of welcome for the Holy Father and to make it a place where he can really recharge his batteries after the longest flight he's ever done,' Mr Casey told commercial radio.

'He was very excited when he got off the plane. He looked a little tired, as you might expect ... but he's very focused and very excited about the week ahead.'

The Pope makes his formal appearance for the week-long World Youth Day celebrations on Thursday, when he arrives in Sydney Harbour in a papal 'boat-a-cade'.

But the city is already full of young pilgrims from around the world preparing for the first official events on Tuesday and organisers are confident that international visitor numbers will reach their target of 125,000.

The event, which has been held in different cities around the globe since 1986 in an attempt to rejuvenate the Catholic church, ends on Sunday with a papal mass expected to draw 500,000 people.

A 3.8-metre cross and 15-kilogramme World Youth Day icon portraying Mary and Jesus completed a journey around Australia Monday, arriving in central Sydney by ferry to be welcomed by hundreds of pilgrims.

'For us, the cross is a message from Christ,' said Italian pilgrim Paola Verde. 'It's a message of hope and love.' -- AFP