A not unlikely scenario, given the game is on matchday 6 and Real may have already qualified by then. However, if we draw with Real at Wembley and then we lose to Dortmund, we go into the final matchday as follows (I'm assuming everyone wins their APOEL games):
Real......11
Spurs..... 8
BVB....... 7
So Real would have to play for at least a draw against Dortmund, since it may be the difference between finish first or second in the group (depending on our respective GD).
If we actually manage to beat Real at Wembley and lose at Dortmund, then it will get really interesting:
Spurs.....10
Real......10
BVB....... 7
A loss by Real, depending on the score, could see them in the Europa League!
The worst case (and unfortunately, most likely) scenario for us is losing both the Real and BVB games:
Real......13
Spurs..... 7
BVB....... 7
In this scenario, I could see BVB getting a win at the Bernabeu and us finishing third, if Dortmund beat us at their home with a score that would give them the tie-break. So I expect Dortmund to go all out in the game against us, which may actually work in our favor, but nothing is guaranteed.
Bottom line: we are not out of the woods yet by any stretch. And if it comes down to winning that last match against APOEL, I worry how jangled the nerves will be! So we must get a good result against Real in a couple of weeks and then we can breath just a little bit easier.