. ♪ all the little birds on jaybird street ♪ ♪ love to hear the robin go tweet, tweet, tweet ♪ ♪ rockingo, rockin' robin >>> you know what that song is about this morning. it is a big day. topping "the pulse," the story everyone's talking about from our house to your house. >> we're delighted to welcome back robin roberts to the air. a comeback we've been waiting for for months. it's happening in a couple of hours at the crossroads of the world. >> marci gonzalez is already there in the heart of things, in times square. and she has the story for us. good morning, marci. >> reporter: good morning, rob and diana. just a few hours away. robin's been preparing by setting her alarm for 3:45 in the morning. she's been doing run-throughs here on the set. all getting ready for her big return. >> i'm coming home. >> reporter: homecoming day for robin roberts. >> the moment we've been waiting for. >> reporter: a long-awaited moment since the "good morning america" anchor shared her diagnosis on-air in june. >> it is something that is called mds, myelodysplastic syndrome. if you're going what? i w