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His last worrying appearance on the X Factor left millions of viewers fearing that Robbie Williams was not up to the challenge of making a big comeback.

But now it seems, the 35-year-old pop star is ready to grace the X Factor stage again – and is being lined up to perform on the grand finale of the ITV talent contest.

Olly Murs will duet with Williams, while Joe McElderry will sing with George Michael and Stacey Solomon will be joined onstage by Canadian crooner Michael Buble.

Beatles legend Sir Paul McCartneywill also perform on the final, which will run over Saturday and Sunday.

For Williams, there will be much to prove after he left fans distinctly underwhelmed with a performance of his number one hit Bodies on the first results show of the series.

It was meant to be his triumphant comeback performance following a spell in rehab battling an addiction to prescription drugs, as he promoted his album, Reality Killed the Video Star.

But wide-eyed, unblinking and glistening with sweat, the singer regularly interrupted his lyrics to shake hands with audience members and address the crowd.

And his performance left many of the 13million viewers wondering if he was quite ready for the challenge.

Afterwards, Williams blamed the performance on a stage malfunction, as the sliding door, which was supposed to open before he sang, failed at the last minute.

He admitted he had battled nerves, saying: 'Now I don't know if you've ever had 10 million (plus) people ready to judge you on your first performance back in three years, but let me tell you, if the door between you and them isn't opening that's enough to throw you right off your stride.'

However, after the 'bizarrely odd start' he started to 'find his feet'.

He added: 'The audience were immense and the love in the room was palpable. It all felt so electric. Like three years of anxiety leaving my body.'

A show source said: 'Everyone has a lot of love for Robbie and it would be a fantastic conclusion to the series if he came back and did an immense performance.

'I have a feeling it would also lay some of his demons to rest.'

The hopefuls were yesterday taken home and Joe, 18, went back to the two-bedroom flat he shares with his mother in South Shields, County Durham, with his mentor Cheryl Cole, who also hails from Newcastle.

And the student, who is the bookmakers favourite to win with odds of 2/5, was bombarded by crowds of adoring fans.

If Joe wins, he will be swept away from his humble background for good. His mother Eileen, 47, has already revealed how he slimmed down to nine stone after binging on sausage rolls, chips and fizzy drinks, at school.

But he lost weight in a bid to get on the X Factor, running three miles every other day and using his mother’s friend’s exercise bike, as well as sticking to a diet of vegetables and low-fat meat.

Welcome home: Joe McElderry and his fellow Geordie, mentor Cheryl Cole caused a stir in South Shields last night

Eileen split from Joe’s father, probation officer Jim McElderry, 47, when Joe was a baby, but said they have a great relationship.

Single mother Stacey Soloman, 19, is second favourite to win the million-pound recording contract at 4/1, while Olly Murs, 25, is at 5/1.

Show sources revealed that Simon Cowell was upset over Danyl Johnson’s departure, saying: 'He really thought that Danyl had done enough to get through to the final.'

Meanwhile, Barry Manilow has hit out at the X Factor contestants, saying they are merely performing high-octane karaoke rather than singing a song.

He said: 'They cram extra notes into each bar and it’s all about vocal acrobatics.'

Daily Mail