Ken Ehrlich, the executive producer of the Grammy Awards, said the star was "really in great shape."
Ehrlich said he'd spoken with Jackson in recent years about performing at the Grammys, but Jackson was never ready.
"I watched this transformation from year-to-year," Ehrlich said, "and the other night it was obvious that he was really ready to get back on stage, perform, and wow people just like he always did."
Early Show co-anchor Maggie Rodriguez said she'd heard reports that Jackson arrived at the rehearsal hours late -- which was not unusual -- but that he was listless and tired. She asked Ehrlich if that was his impression of the icon.
Ehrlich said it was "totally the opposite," adding Jackson didn't arrive late because he was at the Staples Center in meetings. Ehrlich conceded there was a short wait for him to actually get on stage.
"But when he was on stage," Ehrlich said, "it was like he was so intent and so intent on making it work."
Ehrlich added that though the show was still in rehearsal, Jackson was "pretty amazing."
He said, "What really got me was you looked at him, all of a sudden you remembered that every artist, whether it's Justin (Timberlake) or Chris Brown or Usher, and for generations after that, they all came from him. And to see him doing it again was really amazing."
Rodriguez asked Ehrlich about Jackson and his relationship with his children.
Ehrlich said he always worked professionally with Jackson, but Jackson would regularly bring his children to meetings about different projects.
Ehrlich recalled a recent meeting with the children, when Jackson introduced them again to him, and Ehrlich said he saw things differently.
"I just -- all of a sudden, all of the show business, all the entertainment, all of that was aside. He was a father, and he was their father. He was their guardian," he said. "It was pretty amazing to watch him with them because you could see the love both ways."