David Beckham and Victoria Beckham congratulate Romeo Beckham after he completed the Junior Marathon in London.
David Beckham marked his 40th birthday by joining Instagram.
The former England captain posted a picture of himself on the photo sharing website early on Saturday morning.
The caption next to the image, which showed him lying in bed, read: "Good morning and hello! It’s great to finally be on Instagram, been a long time coming but I can’t wait to start sharing all my special moments with you.
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"Thank you for all your birthday messages so far. Looking forward to a great day with friends and family x."
Beckham already has a huge online following through his Facebook, Google+ and YouTube pages.
And within five hours of posting the birthday selfie, he had amassed over one million followers on Instagram.
Beckham and his wife Victoria are celebrating the occasion in Marrakesh, Morocco, along with a number of family and celebrity friends.
Later in the morning Beckham posted a picture of himself on Facebook preparing to open his presents by a pool. "I feel very spoilt this morning! #DB40," he said.
Manchester United wished their former midfielder a happy birthday on Twitter on Saturday morning.
"Happy 40th birthday to #mufc legend David Beckham!" they posted on their official Twitter feed.
AC Milan, with whom Beckham enjoyed two loan spells towards the end of his career, also passed on their congratulations.
They tweeted: "Today David Beckham celebrates his 40th birthday! Buon compleanno David, HBD! #weareacmilan #DB40."
Beckham retired from football in 2013 following a 22-year career which saw him win 15 major trophies.
The former midfielder is England’s most-capped outfield player, with 115 caps.