What can we buy for our One Direction superstar son Liam Payne's birthday?

Geoff and Karen Payne revealed have been wracking their brains for the past few months trying to come up with gift ideas for the One Direction heartthrob and as Geoff admits, it hasn't been an easy task.

"It's getting ever more impossible to buy him things for his birthday," he told the Express & Star. "Me and Karen have been wracking our brains this year.

"He doesn't ask for anything from us to be fair.

"We thought we could buy him a nice watch but he's got about 10 watches already. We've bought him a few small things. That's all we can get him really."

Geoff and Karen have flown over to Chicago to see their globally-adored son who is performing with his bandmates at the Soldier Field football stadium tonight (fri), the oldest NFL stadium in America and the home of the Chicago Bears.

To mark his 20th birthday last year, Bushbury's Liam partied with his girlfriend Sophia Smith at the Funky Buddha nightclub in London.

Today's birthday celebrations are set to be a much calmer affair.

Geoff told us: "Me and Karen are going over to Chicago. His two sisters can't get the time off work so unfortunately they aren't coming.

"The band have a gig which we are going to and then we'll be going out for a meal. It'll just be me and his mum as well as friends if he decides to invite them.

"We don't see him much so we are really looking forward to it.

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"I'm not sure what other plans he has made for his birthday. Hopefully his sisters will be able to celebrate his 21st with him soon."

Former St Peter's Collegiate student Liam and his One Direction bandmates Harry Styles, Niall Horan, Zayn Malik and Louis Tomlinson are well into their 31-date world tour of North America which concludes in Florida in October. Before that they were performing gigs throughout Europe.

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Geoff admitted seeing his son very little since he shot to fame after first appearing on the X Factor in 2010 was still hard to take.

"It's been a tough few years for us," he said. "We've hardly seen Liam in that time. We saw him two weeks ago so it hasn't been too long this time.

"He still pops home when he can but his visits are few and far between. But we really enjoy the time when we're with him.

"He's worked on his last three birthdays and we've not seen him. But as it's his 21st, a special birthday, we wanted to be with him.

"It's a good coincidence that he is turning 21 while in America. He'll be legally coming of age there and he'll be legally allowed to buy a drink at the bar."

It has been a mixed year for One Direction. In May, a controversial video emerged of Zayn and Louis smoking what is believed to have been a joint.

As well as selling out their world Where We Are tour, the band is also working on a fourth album, with a new autobiography entitled Who We Are coming out next month.