That's the day Major League rosters expand, allowing teams to bring in reinforcements from the Minors. The Cubs likely will not make all of their callups at once, as some players will remain at Triple-A Iowa for the team's playoff run.
Eventually, manager Lou Piniella expects to bring up seven or eight players.
"I think you've seen them here before," Piniella said Friday. "I don't think there will be any surprises."
There are several players on the Iowa roster who have spent time with Chicago this season, led by pitcher Jeff Samardzija and first baseman-outfielder Micah Hoffpauir.
Samardzija has appeared mostly in relief in two stints with the big league team this season. His last appearance was a spot start against the Phillies on Aug. 12, when he gave up seven runs in 3 1/3 innings. That raised his ERA to 7.81.
Hoffpauir was on the Cubs' Opening Day roster until he was optioned to Iowa on Aug. 7. He hit .281 with four home runs in April and May, but his production and playing time slipped as the season progressed, and he had one hit in his final 15 at-bats in the big leagues before he was sent to Iowa to get consistent playing time. Hoffpauir was hitting .221 in 21 games with Iowa entering play Sunday, but he did go 2-for-4 with three RBIs on Saturday.
Other pitchers who could be in line for a callup include Justin Berg, Esmailin Caridad and Jeff Stevens, who all have appeared in relief for Chicago this season.
Rule 5 pick David Patton, who pitched a scoreless inning for Iowa on Sunday, was with Chicago until the team placed him on the disabled list with a groin strain on July 5. He could return as well.
The Cubs also are expected to recall infielder Andres Blanco, a defensive specialist who hit .237 in 93 at-bats and has been rehabbing a calf injury in Iowa. Infielder Bobby Scales, who was first called up in May after 11 seasons in the Minors, also could be back.
The Cubs are not expected to bring up any players from levels below Triple-A.
Andrew Simon is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.