Can Chelsea score two goals at home? They most certainly can. It's certainly not beyond them.
But can they keep a clean sheet when they are going after a team at this level of football? That is very difficult to do when you open up against the very best teams - and it always has been.
Paris Saint-Germain look like a team with some players who are goal-getters. I know Zlatan Ibrahimovic is going to be missing, but they still have Edinson Cavani and Javier Pastore, who came on in the first leg and scored a great goal, from his point of view.
So I'm not sure if they will keep a clean sheet. I have said before that they have the best back five in this country, but the goal they conceded to make it 3-1 in the Parc des Princes was very un-Chelsea-ish.
You very rarely see them concede goals like that third one. If you look at this back five over the rest of the season - and before - then you have to say they have defended very well as individuals and collectively, but mistakes can happen at any time and to any team. That back five will need to have a good night on Tuesday.
Going forward, Jose Mourinho opted to start Andre Schurrle last Wednesday because he evidently doesn't feel he has a striker that's good enough. Schurrle may not be a centre-forward, but he clearly feels he's better than what else he's got in that position.
That is quite a criticism of the strikers that are there, but you have to factor in that Mourinho works with these players every day of the week and isn't making his judgments based on the 90 minutes that the rest of us see on a Saturday or Sunday afternoon.
His call was that he felt Schurrle, in that system away from home, was more of a threat than Demba Ba and Fernando Torres. It's very easy to say afterwards that he should have done differently, but you're talking about a serious football manager who has won the very biggest trophies. His judgement is based on what he sees every day in training and I would not be critical of that.
If Samuel Eto'o is fit then I think he will play in the second game - and I think he might have played if he'd been fit last week. The decision is a reflection on how he sees Ba and Torres at Chelsea Football Club at this moment in time.
I wrote last week that I wasn't sure if PSG, who play in a league that is not very strong, could make the step up to this standard and for the first 45 minutes I think my worries were justified.
They need to step up to play quicker football - and by that I mean they have to move the ball quicker and also think quicker - and they found it difficult for 45 minutes.
But in the second half I was proved wrong. I don't know if it was because Chelsea dropped a yard or if PSG found a yard, but they were by far the better team after the break.
I would expect it to be a similar game at Stamford Bridge. I expect Chelsea to start strongly, but this time they need to stay on the front foot.
Mourinho has described the job as "impossible", but of course it isn't. The way to look at it is this: is it impossible for them to score one goal in the first 45 minutes, one goal in the second 45 minutes and another goal, if necessary, in the next half-an-hour? That is certainly not impossible.
But it brings me back to the most difficult part of the job. Can they keep a clean sheet? They can score goals, but can they keep PSG out at the other end while they go in search of those goals?