By Bruce Levine–

CHICAGO (CBS) — Although the news on the field has been great for the surging Cubs, the bad news was the report from the clubhouse. late Thursday.

Shortstop Addison Russell will be out upward of three more weeks after aggravating his right foot injury during a rehab stint at Triple-A Iowa. Russell has plantar fasciitis, the team said, and an MRI confirmed he’ll essentially have to start over in his rehab as he works back.

Russell hasn’t played in a big league game since Aug. 2.

“This is about just getting him ready,” manager Joe Maddon said. “We don’t know how this will play out. He is injured. We will get him well. There is nothing to project upon with him right now. We need to get him well.”

Javier Baez has taken over as the everyday shortstop and played some of the best baseball of his young career. Meanwhile, Russell has struggled for stretches this season, hitting .241 with 10 homers, 36 RBIs and a .722 OPS in 97 games.

Infielder Mike Freeman will be called up from Triple-A on Friday, proving an option for the Cubs to give Baez a break here and there.

Late Thursday, the Cubs made another roster move, acquiring outfielder Leonys Martin in a trade with the Mariners. Chicago will send back cash or a player to be named later.

Martin is hitting .174 this season and had been at Triple-A Tacoma. He has 114 career stolen bases and can provide speed off the Cubs bench in September.

Bruce Levine covers the Cubs and White Sox for 670 The Score and Follow him on Twitter @MLBBruceLevine.