The fashion designer posted a close-up picture of a pink dress on Instagram, writing: 'What to wear in Marakesh?'
She also revealed that it was vintage Yves Saint Laurent and referred to David's birthday bash with the hashtag #DB40.
It's thought that a group of A-list friends will help David celebrate his birthday. The sportsman is said to have invited Tom Cruise, Gordon Ramsay and Guy Ritchie to the do at the luxury Amanjena resort outside the Morrocan city.
David and Victoria will be celebrating the footballer's birthday in Morocco
The hotel is said to hold a special place in Becks' heart after he and Victoria enjoyed a romantic break there in 2004. It certainly has all the high end luxury that the Beckhams could want, with facilities including a 27-hole golf course, a 33-metre pool and a spa which features two Turkish-style hammans.
The entire Beckham family have just returned from an extended to trip to LA. This year the famous clan decided to celebrate Victoria's 41st birthday in their old haunts. Their visit tied in with the launch of her collection at Barneys and also allowed them to attend the Burberry fashion show where little Harper charmed the front row.
Brooklyn had a particularly good time hanging out at the Coachella music festival and also taking his younger brothers to the Nickolodeon Kids' Choice Awards.