Los Angeles: Singer Justin Bieber returned from London to the US to help singer Lionel Richie's daughter and model Sofia Richie celebrate her 18th birthday.

Sofia, who turned 18 on Wednesday, was spotted with Bieber at RAWkin' Juice in Burbank, California, on Tuesday afternoon -- hours after she was seen visiting his Los Angeles home, reports aceshowbiz.com.

According to an eyewitness, Sofia and Bieber looked like a couple during their visit to the juice bar. 

“He was very engaging with her the whole time, he was very attentive. They were the cutest little couple there with a bodyguard. You could just tell they were a couple and he seemed to really care about her," the eyewitness said. 

“They did a taste test of some of the products and he made sure that she was involved. He walked over and gave her a little cup of the sample. Justin was an absolute doll ... I was so distracted by her skin and eyes -- they are amazing,” the eyewitness added.