BARBARA WALTERS may have had a run of bad luck lately, but she’s not ready to be put out to pasture!

The ENQUIRER has learned that the 83-year-old “View” co-host, who’s been sacked by a concussion and the chickenpox in the past two months, is livid that her ABC bosses are already eyeing her replacement – California’s former first lady Maria Shriver!

“BARBARA MAY BE SICK AND FRAIL, but she’s feisty as ever and deter­mined to come back to work,” a source told The ENQUIRER. “She loves Maria and respects her talents, but at the end of the day, she’s as competitive as ever and says she has no plans to give up her day job.”

Maria, 57, resigned as an NBC news anchor when her estranged husband, Arnold Schwarzeneg­ger, was elected governor of the Golden State in 2003. But since filing for divorce in 2011, after it was revealed he’d cheated and fathered a child with their maid, sources say she’s been itching to get back to work.

As The ENQUIRER reported in June, Maria was already in talks with ABC to take over Barbara’s annual “10 Most Fascinating People” specials and revive her famous Academy Awards interview shows.

According to sources, Barbara is also upset with her daughter Jacqueline, who’s been urging her hardworking mother to retire.

“Barbara’s getting a lot of pressure from all her close friends and family to retire and enjoy her golden years,” the source added. “But she feels like she still has a lot of pep in her step, and hearing that Maria is eagerly waiting in the wings has her fired up even more to come back with a vengeance