"Good Morning America" co-host Robin Roberts, second left, with her sister Sally-Ann Roberts, left, and co-hosts Josh Elliott and Lara Spencer. (Fred Lee/AP)

Roberts announced earlier in the week that her last day would be Friday. But, she explained, her 88-year-old mother has had some health issues recently, and she is flying home to Mississippi to be with her family.

“You’re the team captain and the team is going to run in your absence,” newsreader Josh Elliott said. “But you’re never really going to be gone.”

While Roberts is away, co-host fill-ins will include Diane Sawyer, Barbara Walters, Elizabeth Vargas and Katie Couric, ABC added. There will also be special guests on the show who will stop by the set in the coming months, from the “Modern Family” cast to Oprah Winfrey.

Roberts revealed this summer that she had been diagnosed with myelodysplastic syndrome (MDS), a rare blood disorder that affects bone marrow, a condition likely caused by complications with her treatment for breast cancer five years ago.

Calling Roberts the “heart and soul” of “GMA,” ABC news president Ben Sherwood wrote in memo to staff that, “While she’s away, Robin has told us how much she wants the GMA team to keep up the fun, energy and forward momentum. It’s all good medicine for her, she says.”

.Recently, “GMA” has continued been beating the “Today” show in the ratings, including the week after NBC’s highly-rated Olympics.