I would go with Oliver Bierhoff.
First and foremost, he has previous for coming off the bench and having a galvanising influence. The most notable example being the Euros 1996 final between Germany and Czech Republic. When Bierhoff came off the bench, Germany were trailing 1-0 with just 20 minutes to go. It only took him 3-4 minutes to get the equalizer. Talk about an instant impact! The game goes to extra time, and what happens? That's right, Bierhoff scores in extra time which proves to be the winner.
Secondly, its no secret that when teams are desperate for a goal, they tend to be more direct. One of the most direct strategies adopted in football is crosses. Well, when it comes to aerial presence he's one of the best in history as exemplified by:
Even till this day, he has the Serie A record of most goals from headers in a single campaign
Furthermore, we need to think about the mindset a player needs to be expected to make the difference. Remember, this will be when the crowd become restless. Or when your teammates start gesticulating. Confidence is paamount in football, and yet, in these latter stages where a players mental fortitude is challenged. Its this stage of the game where self-doubt creeps in, or players defer to bigger names to take that risk. Now I want to quickly pivot back to what I mentioned in the first paragraph, he scored both the equalizer and the winner. Different things were at stake at both stages of the goals right. With Germany trailing, the headspace being do not lose, but then the headspace following the equalizer lets go for the kill. Now to come back full circle, its important to emphasize that this was a player that was not only far removed from the starting berth, he wasn't even getting cameo appearances as far as the knockout rounds were concerned. Prior to his substitue appearance, he last featured in a group stage game. So for him to do what he did speaks volumes of his mental fortitude.
