Coach a first-time manager through the specific hard conversation they're dreading

Coach me — a first-time manager — through a specific hard feedback conversation I have coming up. Skip the general theory of giving feedback; I need help with this exact conversation.

WHO THIS IS WITH AND THE SITUATION
My direct report has missed three deadlines this month and blames unclear requirements each time, but the requirements were the same as they've always been.

WHAT I'VE TRIED ALREADY, IF ANYTHING
I mentioned it lightly in our last 1:1 as 'let's tighten up on deadlines' and nothing changed.

WHAT I'M SPECIFICALLY AFRAID WILL HAPPEN
I think they'll get defensive and say the team doesn't give them enough support, which will make me feel like I have to apologize instead of holding the line.

WHAT ACTUALLY NEEDS TO CHANGE
They need to flag blockers within 24 hours instead of missing the deadline silently and explaining after the fact.

Start by naming, in one sentence, the core message this conversation needs to land — the one thing that has to be true in their head when they walk out, even if everything else about the conversation goes imperfectly. Then write an opening line that gets to that core message within the first thirty seconds, since first-time managers most often fail by over-cushioning the opening until the actual point gets lost or arrives so late the person has already tuned out waiting for a "but."

Given what I said I'm specifically afraid will happen, write out that reaction as a realistic response, then give me one line to say back to it that neither backs down from the core message nor escalates the tension — a first-time manager's most common mistake here is either caving the moment there's pushback or getting defensive and turning it into an argument.

If I've already tried addressing this and it didn't work, name specifically what about the previous attempt likely failed to land (too vague, too easy to explain away, not tied to a concrete example) before telling me what to do differently this time — repeating the same approach with more emphasis is the single most common mistake managers make on a second attempt.

End with one thing to explicitly avoid saying in this specific conversation, based on the situation described, not a generic feedback no-no list.

OUTPUT FORMAT
1. The core message in one sentence.
2. The opening line.
3. Their likely reaction (given what I'm afraid of) and my one-line response to it.
4. If a prior attempt was described, what likely went wrong with it and what to do differently.
5. One specific thing not to say in this conversation.