Major-league rosters expand to 40 players on September 1, and teams can call up 15 extra players from the minor leagues to give them experience at playing in the major leagues. Every once in awhile, a team gets a steal – after all Francisco Rodriguez was a September call-up for the Anaheim Angels in 2002 and he played a major role in the franchise’s World Series title that October.

Here are six Phillies who could make an impact with the Phillies in September:

6. Carlos Rivero, 3B, Triple-A: Rivero wasn’t highly regarded before the season but he had a solid campaign with the Double-A Reading Phillies, earned Minor League Player of the Month for July, and just recently received a promotion to the Lehigh Valley IronPigs. Rivero plays the hot corner, so he could receive some playing time since Placido Polanco has been decimated with injuries as of late, and neither Michael Martinez nor Wilson Valdez has done an adequate enough job to win the role.

5. Matt Rizzotti, 1B, Double-A: Rizzotti is a massive 6-foot-5, 255-pound first baseman who is thriving in Double-A this year, where he has a .280/.384/.488 line to go with 20 home runs and 68 RBIs in 115 games. He is blocked to the big leagues by Ryan Howard, and he can only play first base (he’s actually best suited in the American League as a DH), so a solid September would make him trade bait for the Phillies.

4. Justin De Fratus, RP, Triple-A: De Fratus has solid numbers in Triple-A (4.34 ERA, 29 IP, 37 K), and he’s got the stuff to be a major-league pitcher soon enough. He was rated by Baseball America as the fifth-best prospect in the Phillies organization prior to the season. He is 6-foot-4 and throws a fastball that reached 96 miles per hour. He served as the closer for the Reading Phillies, and if the Phillies don’t resign Ryan Madson after this year, De Fratus could eventually work his way onto the big-league team as a closer.

3. Phillippe Aumont, RP, Triple-A: Like De Fratus, Aumont will almost certainly get the call-up in September, especially given that the Phillies have had a bullpen plagued with injuries. Aumont is the guy the Phillies got when they let go of Cliff Lee after the 2009 season. He has a 3.14 ERA in 14.1 innings this year with the IronPigs, and he has struck out 24 batters. His WHIP (1.74) is frighteningly high, but he could surprise in September, and the 6-foot-7 pitcher could possibly sneak onto the postseason roster with a strong enough month.

2. Michael Schwimer, RP, Triple-A: I still don’t understand why Schwimer hasn’t been called up to the big leagues. He’s a 6-foot-8 relief pitcher who is absolutely dominating Triple-A (8-1, 1.80 ERA, 10 SV, 83 K in 65 IP, 1.03 WHIP). Surely he is a better option than David Herndon or Scott Mathieson or Drew Carpenter. Schwimer projects to be a similar pitcher to Michael Stutes, and it’s time to see what the big man can do.

1. Domonic Brown, OF, Triple-A: Don’t forget that the fourth-overall prospect in the game prior to the season is still in Triple-A (actually he was just sent back down). He struggled this year in the major leagues, both at the plate – hitting left-handers namely – and in the field, but he still has tons of raw potential, and he’s probably a better option than Ben Francisco. Brown still has a shot to make the postseason roster, and a strong September would really help his case.