Matz hopes to pitch in Florida on Thursday

Mets lefty receives injection in upper back as he tries to get healthy for NLDS

Matz hopes to pitch in Florida on Thursday

NEW YORK -- Mets pitcher Steven Matz received an injection Friday to relax the muscles in his upper back, according to manager Terry Collins, with an eye toward throwing 90-100 pitches in an instructional league game Thursday in Port St. Lucie, Fla.

As of Saturday morning, the Mets still had little idea if Matz would take to the injection quickly enough to complete that assignment, which Collins considers a prerequisite for making his postseason roster. The Mets' preference is still to have Matz start Game 4 of the National League Division Series at Citi Field if he is healthy, but they will use Bartolo Colon in Matz's place if he is not.

"If he can't pitch [Thursday], there's a good chance he won't pitch [in the postseason]," Collins said. "But if he can get an outing this week where he can throw 90 to 100 pitches by midweek, he'll be OK."

Matz has been ailing since early this week, when he woke up with stiffness in his upper back. The Mets initially classified it as a minor injury that would not even cost Matz a start. Since that time, the team has twice scratched Matz with an injury that has now put his postseason in jeopardy.

In six starts overall this season, Matz is 4-0 with a 2.27 ERA. He missed two months earlier this season with a strained left lat muscle, an injury that the Mets consider unrelated to this one.

Anthony DiComo is a reporter for MLB.com. Follow him on Twitter @AnthonyDiComo and Facebook, and listen to his podcast. This story was not subject to the approval of Major League Baseball or its clubs.