Do the mavs have to win game 4 to avoid choking in the series like they did against the heat?

Because if they don't, they'll have to go back to LA for game 5 which would certainly be winnable for a desperate Lakers team, and then their lead would only be 3-2, and the mavs would then be playing to avoid a game 7 on road. Since the mavs would be too dejected about playing game 7 on the road after a 3-0 lead, the lakers really only have to force a game 7 by winning three straight games to take the series.