A majority of morning viewers has greeted the arrival of Savannah Guthrie with a yawn in her first week as "Today" show co-anchor.
NBC's "Today" was beaten last week by ABC archrival "Good Morning America" by 357,000 viewers, the Nielson Co. said.
"GMA" drew an average of 4.57 million viewers, compared with 4.21 million for "Today," according to preliminary Nielsen figures released Monday.
This represents the largest lead by "GMA" over "Today" in more than 17 years, while extending its top-ranked status to three consecutive weeks, ABC said.
Meanwhile, in the 25-to-54 demographic, "GMA" landed just 2,000 viewers behind "Today." It was the narrowest margin in that demo in nearly 17 years, the network said.
Final Nielsen numbers will be released later this week.
"Today" had been the undisputed morning champ in the ratings since 1995 until this spring, when a resurgent "GMA" snapped NBC's winning streak by seizing the top spot several times.
But last week's victory by "GMA" (with its anchor team of Robin Roberts and George Stephanopoulos) seemed particularly striking, since it coincided with the official installation of Guthrie at the "Today" anchor desk alongside longtime co-anchor Matt Lauer.
The "Today" show loss hinted at lukewarm audience interest in Guthrie's arrival. Or perhaps viewers were displaying dismay toward NBC for ousting Ann Curry, who had shared co-anchoring duties with Lauer for just a year. She joined the program in 1997.
"We are incredibly confident in the new 'Today' anchor team," executive producer Jim Bell said. "Although it's premature to look at one week of unofficial numbers and draw any conclusions, we just made a big change that we didn't take lightly, and we are in this for the long run."
Curry's last day as co-anchor was June 28, when she fought back tears and told viewers, "This is not as I expected to ever leave this couch." She now holds the titles of national and international correspondent/anchor and "Today" anchor at large.
Replacement of Curry at "Today" loomed with the end of its 852-consecutive-week supremacy. That winning streak had been a huge point of pride at NBC as the rest of the network's fortunes declined.
Morning shows are also an important cash cow. The "Today" show earned an estimated $484 million in 2011, according to Kantar Media, more than "GMA" ($298 million) and CBS' morning show ($156 million) combined.
Guthrie, who continues as NBC News' chief legal correspondent, joined "Today" last year as co-host of the four-hour program's third hour.
She's been at NBC since 2007, coming from Court TV. She covered Sarah Palin's campaign in 2008 and was NBC's White House correspondent from 2008 to 2011. A graduate of Georgetown Law School, she worked in television for most of her career other than two years spent practicing law in Washington.
The timing of Curry's dismissal, and Guthrie's succession to her role, has been strategic. NBC has wanted to give viewers (and Guthrie's colleagues) a chance to get used to her in her new role before "Today" heads to London later this month for special broadcasts during the Olympics.