New York — Mets pitcher Matt Harvey will be sidelined for several weeks with a stress injury to the scapula bone in the right shoulder, the latest setback to a career already slowed by Tommy John surgery and a Thoracic Outlet Syndrome operation.

The injury-ravaged Mets also put second baseman Neil Walker on the 10-day disabled list with a partially torn left hamstring. He was replaced by infielder Gavin Cecchini, who was recalled Thursday from Triple-A Las Vegas.

The moves came as the below-.500 Mets, who have played well lately, got ready to open a four-game series against NL East-leading Washington.

Mets general manager Sandy Alderson said Harvey is expected to go on the DL Friday. The Mets, reticent to be precise with outlooks of injured players, said only that Harvey and Walker are expected to miss "several weeks."

Alderson said ace Noah Syndergaard, who was expected to be out until after the All-Star break with torn lat muscle, wouldn't be able to throw for four more weeks. He's been on the disabled list since May 1, and Alderson said the timetable didn't reflect any setback.

Harvey, the former Fitch High School star, had a platelet-rich plasma injection at the Hospital for Special Surgery on Thursday, a day after his fastball averaged 91.8 mph against the Chicago Cubs, down from 94-96.5 mph in his previous starts this season, according to Brooks Baseball.

Harvey was pulled after four innings in a 9-4 win over the Cubs.

"I think the last time I threw 87 (mph) with a fastball was probably freshman year of high school," he said after the game.

The former ace is 4-3 with a 5.25 ERA in 13 starts.

"He was complaining about a tired arm, a dead arm," Alderson said.

Alderson said the injury was somewhere between a fracture and a bruise. As for Harvey's return to the rotation, "the amount of time we expect he will be out is measured in weeks, not months," he said.

Mets manager Terry Collins said he spoke with Harvey earlier in the day and "he's disappointed."

But Collins added, "it's still not a bad scenario where you're looking at another surgery."

Harvey had a rib removed last year during the thoracic surgery, aimed to fixing the numbness he'd felt in his hand.

While Harvey's injury was a surprise to the Mets, Walker's problem was not unforeseen.

Walker tried to bunt for a hit in the third inning Wednesday night and pulled up lame on his way to first base. He fell to the ground and later left with a trainer and Collins.

Walker is hitting .270 with nine homers and 33 RBIs.

Alderson estimated Walker could need two-to-three weeks of rehabilitation, then more time to rejoin the Mets. T.J. Rivera started at second base in the series opener against the Nationals.

In other injury news, Alderson said doctors found some "loose bodies" in the elbow of lefty Josh Smoker, who went on the disabled list this week with a strained shoulder.