The 24-year-old has been on the disabled list since July 2 with bursitis in his right pitching shoulder and was in Pittsburgh on Monday to get checked out.
Capps will join Double-A Altoona on Tuesday and pitch one inning in the Curve's game Wednesday. He'll then throw a side session on Thursday to simulate back-to-back performances, Russell said. If all goes well, Capps will join the Pirates in Milwaukee on Saturday.
"It's a little ahead [of schedule], Capps said. "Physically, I feel great. I really do. The ball's coming out of my hand. Now I just got to find my delivery and find the release point, and everything like that."
Capps said his velocity is in the 90-94-mph range and remained that way throughout his 1 2/3 innings for Triple-A Indianapolis on Sunday. In addition, he struck out four of the six batters he faced while making a pair of rehab outing with Altoona. He also made two appearances with the Gulf Coast League Pirates.
"I let the ball go," Capps said. "There was no pain, no discomfort or anything like that."
"He looks good," Russell said. "He's lost weight. He said he's ready to go."
Starter Phil Dumatrait was also in Pittsburgh on Monday and will remain with the parent club for the remainder of the season. The lefty will continue his rehab work with the Pirates.
Dumatrait underwent arthroscopic surgery on his left pitching shoulder on August 8, and returned home to California for nine days before coming back to Pittsburgh.
"I'm just trying to get my motion back," he said. "It's still a little stiff. It's doing alright."
Todd Krise is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.