One Direction Celebrates Liam Payne 20th Birthday...But Liam Has To Shoot A Video All Day, Looks Upset, Tired

One Direction boy-bander Liam Payne just celebrated his 20th birthday.

However, Liam had to work all day on his birthday and seemed upset, or perhaps distracted and tired. There was a sad slump in his shoulders as the boys shot a new music video.

On Liam's birthday, One Direction's film "This Is Us" opened in the UK....could the stress be wearing him down?

The 1D boys marked the occasion on social media. Liam Tweeted,

"Good morning everyone :)," Liam tweeted, "can't quite believe my life there's no bigger birthday present than what you've done for me in 3 years thank you xx"

Generously, Liam doesn't want gifts for this birthday-just donations to a charity. One Direction fans are urged to give to Trekstock, a nonprofit devoted towards funding cancer research.

"If anyone was planning on buying me anything this is the 1st place u should go https://trekstock.com/donate-now ," Liam wrote on Twitter. "you could make difference to somebody"

One Direction celebrated Liam Payne's birthday by filming One Direction's latest new music video. Liam and girlfriend Sophie Smith were spotted holding hands at the video shoot. Liam filmed scenes for the new video throughout London with bandmates Harry Styles, Zayn Malik, Niall Horan and Louis Tomlinson.

In one scene, the boys kicked a football around.

In another, Harry donned an apron for a scene in a chip shop.

Liam looked a bit distracted and sad-was he upset about having to work on his birthday?

Liam was very quiet on the set, inside sources say, not saying much to the other boys.

The pensive Liam Payne isn't a teenager anymore...but working is hardly a way to celebrate your birthday. Liam just went through the motions at the shoot.

The One Direction boys celebrated Liam's birthday with him on Twitter, perhaps trying to cheer him up.

Harry Styles wished his bandmate a happy birthday, writing "@Real_Liam_Payne is now 20 years old. Which means he is suddenly wiser and more manly than he was before. Happy birthday man. .xx."

Niall Horan also wished his 1D bro a great b-day, Tweeting, "Happy birthday to my brother @Real_Liam_Payne ! No longer a teenager buddie! love you dude !"

The One Direction boys are on a This Is Us press tour in anticipation of the film's release.

Do you think Liam was OK with working on his birthday?

What would you get Liam for his birthday if you could? Will you donate to his charity? Sound off in the comments below!