The 30-year-old singer put the unnamed man in the recovery position after he collapsed in the path of oncoming traffic, reported Contactmusic.
"Sarah was driving around the island in a hire car when she saw this young guy passed out on his back with vomit around him. She slammed on her brakes and rushed over to him to see if he was OK. Luckily, he was still breathing, but she was worried he might choke if he was sick so she put him on his side in the recovery position and then flagged a passing car down for assistance," a source said.
"A local then called an ambulance for him and the guy was taken to hospital. The medics said he would have to have his stomach pumped, and thanked Sarah for stepping in. If he had been sick while he was lying on his back he could have choked to death," it added.