Matz has suffered a partially torn left lat muscle, and will miss at least three weeks, Mike Vorkunov of The Star-Ledger reports. The Mets are now officially confirming the injury, and the 25-year-old hurler has already received a PRP injection. He won't be able to start throwing for three weeks, at which point he will be re-examined. He's likely more than a month from a return, so the Mets will likely return to a five-man rotation. Either Bartolo Colon or Jon Niese are expected to start in his place Saturday.