There are seven bullpen pitchers who will be travelling with the team today, Ryan Pressly, Josh Roenicke, Tim Wood, Tyler Robertson , Anthony Slama, Luis Perdomo, and Bryan Augenstein.
Pressly is the Twins rule 5 pick. He apparently has a good fastball. His challenge will be to demonstrate not only can he throw strikes with it, but can locate it within the strike zone.
Roenicke was grabbed on waivers last fall. Wood was signed to a minor league contract and then added to the roster to protect him from the rule 5 draft. Robertson is a former supplemental first round draft choice. He is devastating against lefties, but struggles against right handed hitters.
Slama, Perdomo and Augenstein are all non-roster invitees. Perdomo has a great fastball, but doesn't throw strikes consistently. Slama has shown he can get minor league hitters out. There are some questions about whether his funky delivery will fool major league hitters. Augenstein was a minor league free agent.
Slama, Augenstein and Perdomo are also on the list for Sunday's game. I would guess that makes them the last three guys expected to get work today. If the two starters each work a couple innings and the other four relievers can take an inning, they will get 8 innings. Slama, Perdomo and Augenstein would pitch a ninth inning if needed or if the others hit their pitch count before getting their innings in.
That is mostly speculation, but it is the sort of reading tea leaves that you have to do during spring training to determine how the team views various pitchers. Guys pitching at the end of the game are usually at the end of the pecking order at this time of year. Their job is to take the opportunities they are given and open some eyes.