Pennant's facial expression the shifty look of a man who has sped past a speed gun and wondered why there was no flash did more than the slow motion television replays to suggest that Lee Probert's decision to award a free-kick was indeed a poor one.
The referee also made a mistake in failing to stop Stoke from pinching a few yards, moving the ball to a more dangerous launching site nearer the Villa area.
Petrov, maybe understandably, was furious. The gist of his post-match polemic? Of course the players understand the referee has a tough job, but if they want respect, they have to stop making such silly mistakes.
'But at the end of the day', 'there's no point complaining', 'we were 1-0 up and couldn't see the match through', 'we have to blame ourselves', and so on. You've heard it all before.
Common enough gripes, certainly, but Petrov has a point. When Probert looks back at the tape he will be should be, at least self-critical. How he failed to spot Jonathan Walters intentionally trip Petrov in the Stoke area as the Villa midfielder made to collect a short corner was especially confusing. Walters stuck his leg out in the most cynical fashion directly in front of Probert, who somehow failed to see the offence.
The sense of injustice will certainly linger, but Petrov knew that his side should never have been in that position in the first place. Had Ashley Young scored rather than put his header from close range wide, well, it would have been a different story altogether. But again, Villa demonstrated a disturbing lack of clarity as the match wore on, and allowed Stoke to launch their final attack.
Martin O'Neill used to say of wrapping up a tied game: 'If you can't win it, just don't lose it.' He would have been apoplectic, therefore, had it been him and not Kevin MacDonald in the technical area when Luke Young launched a speculative long-ball into the Stoke area in stoppage time. Stoke regained possession, found Pennant on the wing, and you know the rest.
But it cannot help the players, being uncertain as to when their new manager, Gerard Houllier, will arrive. It is no use getting by with ad hoc arrangements; they need consistent direction.
'It is complicated,' Petrov conceded. 'Complicated for the new manager, complicated for Kev as well, but there is a solution and we will see the new manager soon. He knows what he needs to do. We wait to see how we can improve.'