What is the most crucial key matchup

With all the downtime between rounds, the media has had a field day reporting (and sometimes creating) all the different storylines, narratives and "key matchups" that the Pittsburgh Penguins and Boston Bruins will have to win in order to have the edge on the series.

In no particular order, we've seen the following things spotlighted:

• The play of trade deadline adds (namely: Jarome Iginla and Jaromir Jagr sub-plots)
• Faceoffs (with the Sidney Crosby vs. Patrice Bergeron subplot)
• 4th line play and depth for secondary scoring and the boost given there
• Zdeno Chara vs. Crosby or Evgeni Malkin?
• Health of the Boston blueline
• The Penguins excellent power play vs. The Boston excellent penalty kill
• Rask vs. Vokoun

I think that covers the major ones, so now we'll go to a poll to see what you think the most important matchup is? It's a easy (but true) cop-out to go for the goalie matchup, because the goalie that plays better is the one that almost always moves on, so we'll drop that and stick to the other points.