PITTSBURGH -- Cubs shortstop Starlin Castro was allowed to walk without a supportive walking boot on his left ankle Friday, and predicts he'll be back before the season ends. Meanwhile, Anthony Rizzo continued to make progress in his rehab from a lower back strain, and was able to run the bases for the first time on Friday.
Castro, who suffered a high ankle sprain on Sept. 2 in an awkward slide at home, said it's important for him to get some at-bats in the final two weeks.
"This is a great season for me," said Castro, who is batting .292. "I think I can improve more than what I've done. I want to be healthy, I don't want to go into the offseason not playing. I want to play -- if it's three games, I'll play three games."
Rizzo has not played since he left the Cubs' Aug. 26 game in Cincinnati when his back tightened up. Manager Rick Renteria said the first baseman most likely will not return until Monday, when the team returns home to face the Reds.
"Obviously, we're taking it very slow," Rizzo said before Friday's opener vs. the Pirates. "We want it to be 100 percent going forward. We don't want any setbacks."
Rizzo did take batting practice for the second day, but running was a new part of his rehab.
"It was nice to throw cleats on and sweat like that," he said.
• Rookie Jorge Soler returned to Miami on Friday for the birth of his first child, and was expected to rejoin the Cubs in Chicago on Monday.
Carrie Muskat is a reporter for MLB.com. She writes a blog, Muskat Ramblings, and you can follow her on Twitter @CarrieMuskat. This story was not subject to the approval of Major League Baseball or its clubs.