ABC's Robin Roberts has received floods of messages from fans and friends after announcing her blood and bone marrow disorder this week.

Five years after battling breast cancer, Roberts, 51, announced Monday she would begin chemotherapy for myelodysplastic syndrome. Also known as MDS, the disease affects blood and bone marrow and was once referred to as pre-leukemia.

The "Good Morning America" co-host also revealed that she would receive a bone marrow transplant from her older sister, Sally Ann Roberts, sometime this fall.

Immediately following Roberts' announcement, messages of support and prayers flooded social media sites from both fellow celebrities and loyal viewers of "GMA." In response to the outpouring of messages Roberts gratefully thanked everyone, noting how much the messages have helped her.

"I slept like a baby last night for the first night since my diagnosis," she said at the top of "GMA" Tuesday morning. "My family and I are overwhelmed and comforted by the response from everyone."

Among the dozens of celebrities and leaders who sounded off on social media sites, Michelle Obama also wished the co-host the best.

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"Barack and I have you in our prayers," wrote the First Lady on her Twitter account. "We believe in you and thank you for bringing awareness and hope to others."

More over, thousands of fans sounded off wishing Roberts and full recovery, including television show hosts Maria Menounos and Brooke Burke-Charvet.

"sending @RobinRoberts lots of love and prayers," wrote "Extra" host Maria Menounos.

"Dancing with the Stars" co-host Brooke Burke-Charvet quoted the "GMA" co-host, posting on Twitter: "Robin Roberts quote, 'Focus on the fight not the fright!' Words to live by… we love you."

Fellow cancer survivor and world class athlete Lance Armstrong wrote, "Wishing my friend @RobinRoberts strength and courage for the days ahead. We're pulling for you. #LIVESTRONG"

"@RobinRoberts @dariofranchitti & I send our love & support," wrote Ashley Judd on behalf of her and her husband. "We are rooting for you & your resilience & well-being."

"I've always been a fighter, and with all of your prayers and support, a winner," Roberts told fans during "GMA" Monday. "My doctors tell me I'm going to beat this, and I know it's true."