At 0-3 down and with nothing to lose, they will possibly seek to throw caution to the wind. That's what normally happens, anyway. If they get the first goal then there will be a slight surge of hope for them and of worry for us. Again, that's what normally happens, anyway.
Personally, I think the best approach is to keep our shape, drop off deep if in doubt, but make absolutely certain to demonstrate a threat on the break. Even if we don't create anything, so long as they know we can break away at any time, that should put enough doubt in their minds to prevent them flooding all over us. Get to the hour mark goalless and they'll either give up or leave such wide open gaps that it would be rude not to score against them.