JUSTIN BIEBER turned basketball Baby-sitter on Thursday (27Dec12) when he agreed to look after Los Angeles Clippers star CHRIS PAUL's three-year-old son as daddy's team took on the Boston Celtics.

The 18-year-old pop star was spotted courtside at the Staples Center in Los Angeles with Paul's namesake kid on his knee.

A nearby Clippers fan says, "Justin appeared to be more than happy to hang out with young Chris. The pair were smiling, giggling and playing - and cheering on dad's team as they crushed the Celtics 106-77."

Bieber is no stranger to looking after little kids - as well as visits to members of his young army of fans, the Baby singer has two siblings, Jaxon and Jazmyn, who are four and three respectively.