Three years ago, after many personal problems — including battles with substance abuse and a broken marriage — that were aired in public, Whitney Houston got a call from legendary record producer Clive Davis, a longtime friend and business partner.

Davis had a simple message for the Grammy-winning, multiplatinum diva, as he told MTV News in an interview. "I said, 'Whitney, it's time to get back to work.' "

On Wednesday (September 9), Houston's album, I Look to You, debuted in the top spot on the Billboard 200. "It was so special to find out today that Whitney's album enters the charts at #1, not only here but in almost every country that it's been released outside of the United States," Davis said. "It's #1 in Germany, Italy, Austria and Spain. It was really thrilling because you don't know how much she was missed and this is a resounding 'Yes.' "

But her comeback has not been without its bumps. Last week, during a performance on "Good Morning America," Houston struggled through a four-song set as her voice wavered. At one point she was forced to point her microphone into the crowd for assistance with the vocals. Like Houston before him, Davis blamed the performance on an earlier, three-hour interview with Oprah Winfrey, as well as separate shoots for two music videos that each didn't wrap until 6 a.m.

"She electrified the audience even though her upper register was not traditional as far as Whitney Houston is concerned," Davis said. "Plain and simple, she was a trooper."

Davis continued, "Two days later, with some rest, when she did 'I Didn't Know My Own Strength' on the 'Oprah' show in Chicago — which I was there and saw — I understand Oprah's Twitter from this weekend."

"In search of ceiling repairmen," Oprah wrote. "Cause Whitney just blew the roof off of Harpo [studio]. Grown men and women weeping in the aisles."

Despite that success, Davis said fans should not expect a comeback tour anytime soon. "Next year I'm sure you'll see her in performance [in different cities]," he said. "She does love to perform. But whether she loves to tour or not, and that grind, I can't testify to that."