Gonzalez underwent shoulder surgery Wednesday and will be out for 9-to-12 months.

Gonzalez (shoulder) returned to his rehabilitation assignment at Triple-A Charlotte after having a setback earlier this week, Phil Thompson of the Chicago Tribune reports.

Gonzalez has been experiencing discomfort in his injured shoulder, Daryl Van Schouwen of the Chicago Sun-Times reports.

Gonzalez (shoulder) allowed one hit and one walk while striking out one over three innings for Triple-A Charlotte on Sunday.

Gonzalez (shoulder) expects to make three or four starts while on rehabilitation assignment with a priority to fine-tune his curveball, Tom Musick of the Chicago Sun-Times reports.

Gonzalez (shoulder) will start a rehab assignment with Triple-A Charlotte on Sunday.

Gonzalez (shoulder) threw a two-inning, 30-pitch simulated game Tuesday, Colleen Kane of the Chicago Tribune reports.

Gonzalez (shoulder) threw 25 pitches in a simulated game Saturday.

Gonzalez (shoulder) completed a bullpen session Sunday, Scott Merkin of MLB.com reports.

Manager Rick Renteria said Gonzalez (shoulder) suffered a "little setback" Friday, but the right-hander will try and resume throwing Tuesday, Scott Merkin of MLB.com reports.