In celebration of his new album, 'Band of Brothers,' Willie Nelson surprised fans with a very special guest at his Boston show on June 17.

A-list actor Johnny Depp took the stage to play guitar for Nelson's entire set -- and it wasn't the first time. The 'Pirates of the Caribbean' star -- who just so happens to be a longtime friend of the country legend -- also appeared 'incognito' during one a Texas concert in March.

This time, Nelson & Family were in town to play a concert with Alison Krauss at the the Blue Hills Bank Pavilion when, much to everyone's surprise, the Red Headed Stranger pulled Depp onstage. And, the singer did it without so much as a whisper to Depp's considerable fame. According to People, when Nelson introduced his bandmates, he just used the well-known actor's first name, and concertgoers barely noticed Depp on stage, even when he had is very own guitar solo!

Dressed in jeans and a simple black T-shirt, Depp looked just like a member of Nelson's backing band. Even throwing in the occasional backing vocals, the 'Transcendence' actor could have gotten away with it, too ... if only his face wasn't known by millions of people all over the world. After the show, the boys snapped a picture for Nelson's Instagram account with Shotgun Willie adding the caption: "From last night, some good looking fellas."

Good looking, indeed!