NEW YORK -- Sidelined starter Steven Matz could rejoin the New York Mets this week "with an opportunity to pitch," manager Terry Collins said Sunday before the club took on the Minnesota Twins at Citi Field.

Matz is hindered by a shoulder impingement and has not pitched in a game since Aug. 14. He threw a pain-free 30-pitch bullpen session that included every pitch in his arsenal on Saturday at the team complex in Port St. Lucie, Florida. Sunday was a scheduled off day in his rehab.

Matz was 9-8 with a 3.40 ERA when he was sidelined. The long-term goal would be to have him a viable option to pitch in a possible postseason.

The Mets would like to see Matz slot in to the rotation spot that was going against the Twins on Sunday, a spot that Collins will use members of his 12-man bullpen to fill. It next comes around on Friday against the Philadelphia Phillies at Citi Field. And Collins acknowledged that if Matz pitches, he will be restricted.

"We have no plans yet. Nothing's written. Steven Matz's name certainly will be in the mix," Collins said. "But Steven, when he gets here, is going to be a guy with a limit in workload that he has. So to get him built up and get him where we want, I am not sure we have the starts available."

Collins said that Matz will be back at the team complex on Monday.

"I think tomorrow when he shows up, we'll know more," Collins said. "But we certainly hope that this week he's up here with an opportunity to pitch."

Flores hasn't progressed: Wilmer Flores' right wrist is still ailing. He attempted to swing a bat and reported he couldn't, Collins said. Flores injured it eight days ago while colliding with Braves catcher A.J. Pierzynski in Atlanta and had a cortisone injection Thursday to address the inflammation. ... Lucas Duda was starting his first game since May. He returned from a stress fracture in his lower back on Saturday. ... Neil Walker said the symptoms he was suffering because of a herniated disk have lessened since surgery. He also said the Mets have not contacted his representatives as general manager Sandy Alderson said they would last month.