And So It Goes,' Billy Joel revealed there was "bad blood" after Elton John suggested he go to rehab. The second part of the doc. will premiere on Friday, July 25 at 8 p.m. ET.

Billy Joel is opening up about a tough moment with longtime friend and tourmate Elton John. In the second part of the new two-part HBO Documentary, "Billy Joel: And So It Goes," the "New York State of Mind" singer shared how John's public comments that he needed rehab strained their friendship.

Billy, 76, revealed in his documentary Billy Joel: And So It Goes, which aired its second part on Friday, that he was ‘really hurt’ by comments made by Sir Elton. The duo had been on their Face to Face tour, which they kicked off in 1994,when Sir Elton addressed several cancellations in an interview with Rolling Stone.