Here are 10 pivotal matchups to look out for when the World Series begins Wednesday night:

1. Red Sox hitters vs. the Cardinals bullpen

Let’s get right to it: Boston is in the World Series because of the damage done to Detroit's bullpen. Eleven of Boston’s 19 runs were plated with a reliever on the mound, including both the grand slams hit by David Ortiz and Shane Victorino.

But while bullpen depth was an Achilles’ heel for Detroit, the Cardinals are a completely different challenge, with a wave of relievers, each seemingly throwing harder than the last. The average fastball velocity for some of the St. Louis relievers (per FanGraphs):

Carlos Martinez 97.6 mph

John Axford 95.3 mph

Kevin Siegrist 95 mph

Seth Maness 90.4 mph

Trevor Rosenthal 96.4 mph

So far in the postseason, the Cardinals bullpen has allowed only six earned runs in 19 innings, with 23 strikeouts.