A brief examination of the rules to help us figure out who we could possibly expect.

There's a lot of debate, in certain circles, about the merits of the September roster expansion rules.  Detractors argue it favors big-market clubs because at the root of it all, the more players you call up the more money it costs, and also that it's unfair for a contender to lose (or win, for that matter) a game that goes to extra innings due to the advantage of additional pitcher.  But for my money, I enjoy the rule.  It allows us to see some potential impact players of the future, and for teams that are out of the running that can sometimes be the only draw they have at the end of the season.

Okay, let's get to the rules.

1.  You can call up as many players as you want as long as they're on the 40-man roster.  That's right, you can technically have 40 players, although most teams top off around 31.

2.  If you want to call up someone NOT on the 40-man roster and it's already full, in order to take that spot the team will need to pass a player through waivers.

3.  Service time rolls on anyone called up, just like at any other time of the year.

Based on those basics, these are the players currently available for the Twins to call up in September:

Pitchers:  Julio DePaula, Philip Humber, Bobby Korecky, Jose Mijares, Pat Neshek*, Oswaldo Sosa
Catchers:  Jose Morales
Infielders:  Matt Macri, Sergio Santos, Matt Tolbert*
Outfielders:  Michael Cuddyer*, Jason Pridie

* = On Disabled List

For those of you who haven't counted, the Twins have 37 players on the 40-man roster.  This means that if they want to call up somebody not on the list above (like Luke Hughes, Kevin Mulvey, Bobby Kielty or Garrett Jones for example), they have a bit of room to with which to work.  What we have to keep in mind is that anyone called up will not only see their service time start to tick (a bit of a touchy subject with the Twins for certain players over recent years), but also that filling up all forty spots restricts what kinds of roster alterations Minnesota can make without being forced to pass someone through waivers.

My predictions:

Philip Humber and Bobby Korecky for pitchers--we know the Twins are looking for a little pitching depth in the bullpen, due to both the current 'pen being a bit shaky and the starters not getting through seven innings often enough.

The Twins will definitely call up a third catcher, and unless they're willing to dip into their three open slots on the 40-man roster for somebody like Ryan Jorgensen or Drew Butera, it will be Jose Morales.  If he's available...which realistically he may not be, as he's listed on Rochester's 7-day disabled list.

For infielders, both Sergio Santos and Matt Macri will likey make appearances to provide infield depth, although the Twins may just go with Macri and wait for Matt Tolbert to get healthy.

Finally, in the outfield I can see Jason Pridie getting a call if the Twins don't believe Michael Cuddyer will be ready by the end of September.

Overall, I see the Twins adding two pitchers, a catcher, two infielders and one outfielder.