Grammy-winning singer Natalie Cole, whose biggest hit came in a virtual duet with her late father, pop legend Nat King Cole, of his decades-old hit "Unforgettable," has died at the age of 65, her family said on Friday.

The family's statement said Cole died on Thursday night at Cedars-Sinai Hospital in Los Angeles from "ongoing health issues."

Cole's career spanned five decades in the R&B, soul, jazz and pop genres. In 2015, she had canceled appearances citing medical reasons.

"It is with heavy hearts that we bring to you all the news of our Mother and sister's passing," the Cole family statement said. "Natalie fought a fierce, courageous battle, dying how she lived - with dignity, strength and honor. Our beloved Mother and sister will be greatly missed and remain UNFORGETTABLE in our hearts forever.”

The statement was signed by Cole's only child, Robert Yancey, and her twin sisters, Timolin and Casey Cole.

Tributes quickly poured in for Cole, with singer Tony Bennett saying on Instagram he was "deeply saddened to hear of the passing of Natalie Cole, as I have cherished the long friendship I had with her, her father Nat, and the family over the years."

Bennett added: "Natalie was an exceptional jazz singer and it was an honor to have recorded and performed with her on several occasions."

"UNFORGETTABLE" COMEBACK

Cole broke out in 1975 with the hit "This Will Be," which won the Grammy for best R&B female performance and also earned her the Grammy for best new artist. Critics compared her to Diana Ross and Aretha Franklin but her career floundered in the 1980s when she ran into problems with heroin.

She bounced back, and her career reached the superstar level in 1991 when she recorded "Unforgettable ... With Love." The album contained songs associated with her father, the silky-voiced baritone who was one of the most popular performers of the 1940s and '50s but died before his daughter began her solo career.

Using technology that was cutting edge at the time, studio engineers merged her voice with her father's in the song "Unforgettable," which had been a hit for Nat King Cole in 1951. The result was a moving, sentimental No. 1 hit 40 years later, that actually sounded as if the two were singing a duet.

The song and the album it came from earned Cole three Grammy Awards.

"I thank my dad for leaving me such a wonderful, wonderful heritage," Cole said in accepting her awards.

Cole's other hits included "Everlasting," "Sophisticated Lady," "I've Got love on My Mind," and "Good to Be Back." In all, she won nine Grammys.

The success of "Unforgettable" capped her comeback after a dark period of heroin, crack and alcohol abuse. In "Angel on My Shoulder," her 2000 memoir, Cole said she turned to drugs because of unresolved issues in her life, including being molested as a child and her father's death when she was 15.

She spent six months in a rehabilitation program at the Hazelden Clinic in Minnesota and told CBS in 2006 that "those people gave me my life back one day at a time."

Cole was diagnosed with hepatitis in 2008 from sharing needles with drug addicts, and underwent kidney transplant surgery in 2009. This past autumn, she canceled several concerts scheduled for November and December, citing a recent medical procedure.

Her 2008 album of pop standards, "Still Unforgettable," included another duet with her father, "Walkin' My Baby Back Home." Her most recent work was 2013's "Natalie Cole en Espanol."

Cole was only 11 when she first sang professionally, with her father. But she went to the University of Massachusetts in Amherst with no plans of an entertainment career. While in college, she performed with bands and set aside plans for being a child psychologist.

Cole's mother, Maria Cole, also had been a singer with the Duke Ellington and Count Basie bands.

Cole portrayed herself in "Livin' for Love: The Natalie Cole Story," a 2000 television movie that depicted her drug addiction. She was married three times.

"We’ve lost a wonderful, highly cherished artist and our heartfelt condolences go out to Natalie’s family, friends, her many collaborators, as well as to all who have been entertained by her exceptional talent," Neil Portnow, president of the National Academy of Recording Arts and Sciences.

Singer Patti LaBelle tweeted “Sending prayers and condolences to all the loved ones of my friend #NatalieCole! She will be truly missed but her light will shine forever!”

Singer Lenny Kravitz posted on Instagram: "As the new year was ushered in, an angelic instrument moved on. Natalie Cole's voice was perfection. And what a lady... You will be missed my dear. Love."