Katie Couric’s heavily promoted return to morning television did not result in a ratings win for ABC’s Good Morning America. On Monday, the first day of Couric’s week-long stint on GMA, ABC’s morning program averaged 4.78 million viewers to 5.11 million for NBC’s Today, according to fast-national ratings. In adults 25-54, GMA pulled 1.76 million viewers (1.5 rating) to Today‘s 2.20 million (1.8 rating).

Ironically, in the last Monday for which final ratings have been released, March 19, GMA edged Today (4.974 million vs. 4.926 million) with regular female host Robin Roberts. Today threw in a mystery “Today legend” stunt against Couric’s GMA debut on Monday, which turned out to be Meredith Vieira. The NBC morning show will likely repeat its ratings victory on Tuesday with Sarah Palin’s headline-making guest hosting turn. Preliminary ratings for CBS This Morning‘s Monday edition, which featured an interview with Oprah Winfrey, are not available yet.