Join us at LeftFootForward, LabourList, Liberal Conspiracy and elsewhere for live debate blogging.
The debate being shown on news channels means that at least three times as many people will see the debates first through the news at ten coverage than in the live coverage itself.
So the news clips and soundbites will matter much more than when the ITV debate had a large audience watching much or all of it.
Given that, it would be much better if the main news bulletins were top open with a 5-6 minute package of straight debate reporting, instead of giving us the instant polling results and post-match analysis first.
And winning in the post-debate polls may matter even more than last week, when a strong points victory for Clegg turned into one of the great conquests over the next 48 hours.
That might be difficult for Labour, whose supporters will I think be under-represented among debate watchers. And weighting for that is tricky, when debate watchers and non-watchers of similar demographics might be different in salient ways.