Michael Strahan Blindsided Kelly Ripa ... No Warning

Michael Strahan dropped a bomb on co-host Kelly Ripa after their show Tuesday ... telling her for the first time he was leaving their show.

Sources connected with the production tell TMZ, Michael sat down with Kelly and Executive Producer Michael Gelman at 10:30 AM and let them know he was leaving 'Live' for 'GMA.'

We're told Kelly and Gelman were "stunned and upset" at the news. And, we're told, since no one on the show had advance warning, there is absolutely no plan on replacing Michael.

In Michael's defense, this was a top secret move on Disney's part, orchestrated by CEO Bob Iger. Sources connected to the deal tell us Gelman might not be aware of the replacement plan, but Disney absolutely has one ... and it assured Strahan of that.