With my psychobabble hat on, could it be argued that it would be better to go into the 2nd leg a goal down rather than a goal up?
If we go into the 2nd leg a goal up, I assume Puel will be tempted to set up the team to protect the lead rather than extend it (and we all know how that will end up...), whereas, if we go into the game a goal down we'll have no choice but to set ourselves up to attack.
Hmm, on reflection, I probably ought to be locked up for thinking out loud and spouting such nonsense...