Kourtney Kardashian and Scott Disick's son Mason spent Saturday in the care of one very special babysitter. Pop superstar Justin Bieber shared a photo of himself playing with five-year-old Mason as the pair soaked up the sun at a pool party.
"Mason is cool as a fan," 21-year-old Justin captioned the photo, which showed him about to give the youngster a piggyback through the water.
Justin spent a sunny Saturday with five-year-old Mason
The sweet picture was later shared by mum-of-three Kourtney and Mason's grandmother Kris Jenner.
"#Mason & @JustinBieber family pool day!!!" Kardashian matriarch Kris wrote alongside the photo. "#bestbabysitterintheworld"
It is thought that Justin has become closer to the famous reality TV family since his road manager Corey Gamble became romantically involved with 59-year-old Kris.
Justin pictured with Kendall and Kris Jenner
The pair have had an on-off relationship after it was confirmed that Kris and her husband Bruce Jenner had divorced in March 2013, and although it was reported that the pair had recently split, they are clearly still good friends and enjoyed a lunch date just last week.
Mason's day out with Justin came shortly after his dad Scott clarified rumours about his recent stay in rehab.
While some of businessman Scott's fans were surprised when he left a facility in Costa Rica after just a week, the 31-year-old insisted that that was the length of time he had always planned to stay there.
"The truth was, I was going for a week for one treatment that they have there," he told People magazine. "I'm not done.
"I plan to go back to this place," he added. "It's an amazing place. It's beautiful and I love it, but I wasn't able to spend three or four weeks there right now. I never planned on it and everyone keeps telling me that I dropped out early.
Kris shared this picture to wish Justin a happy 21st birthday on 1 March
New York-born Scott went on to discuss the benefits of the rehab centre, calling it "very therapeutic".
"It helped my dramatically to see some of the things that have troubled me in the past," he said. "I hope it helps me even more to get to a point where I'm fully cured of some of things that I struggle with."