Celine Dion Leans On Best Friend Shania Twain as She Plans 'Miracle Comeback' Amid Debilitating Health Diagnosis

"The Power Of Love" exists in friendships too!

Celine Dion has apparently been leaning on her longtime pal Shania Twain during this challenging time in her life as she struggles to fight symptoms of her devastating stiff-person syndrome diagnosis in order to make a "miracle comeback" in her career.

"Celine and Shania have been close for years," a source spilled to a news publication on Tuesday, May 30, just days after Dion announced the cancellation of her Courage World Tour on Friday, May 26. "They have quietly supported each other and been confidantes for decades."

"Shania wants Celine to know she is not alone," the source continued, as Dion is inevitably heartbroken by her debilitating neurological disorder. “Because it’s a lonely struggle to go through, especially when you are trying to keep the fight private."

Twain specifically showed up as a true friend for Dion, 55, after the "My Heart Will Go On" singer's husband and manager, René Angelil, died of throat cancer in January 2016, two days before his 74th birthday.

The "You're Still The One" singer was there for Dion to help guide her through life as an independent, single woman in the spotlight following her husband's passing.

Never miss a story — sign up for the OK! newsletter to stay up-to-date on the best of what OK! has to offer. It’s gossip too good to wait for!

"These were things that Shania went through as well after her divorce," the insider noted of Twain, who finalized her divorce from Robert "Mutt" Lange in 2010 before tying the knot with Frédéric Thiébaud the following year.

"Celine plans to write a comeback story for the ages and make René proud from above," a friend of the "It's All Coming Back to Me Now" vocalist explained of the widow. "She isn’t going to retire without a fight."

"She’s refusing to accept defeat," another source declared.

Dion confirmed she's "not giving up" in a heartfelt social media statement to fans regarding the cancellation of her world tour, as OK! previously reported.

The superstar's message read: "I’m so sorry to disappoint all of you once again. I’m working really hard to build back my strength, but touring can be very difficult even when you’re 100 [percent]. It’s not fair to you to keep postponing the shows, and even though it breaks my heart, it’s best that we cancel everything now until I’m really ready to be back on stage again. I want you all to know, I’m not giving up… and I can’t wait to see you again!' – Celine xx."

Radar spoke to sources regarding Dion and Twain's friendship.