From the moment Manchester City named Martin Demichelis in their team to man mark Lionel Messi you sensed danger.
And so it proved. The Argentine defender was sent-off for denying Messi a clear goalscoring opportunity.
The Barca star dusted himself down and tucked the penalty away himself.
Replays seem to show that the initial contact took place outside the box. That would have had no bearing on the red card, but it probably should have been a free-kick rather than a penalty.