NEW YORK -- On a night when they got third baseman Jake Lamb back following more than six weeks on the disabled list, the D-backs watched outfielder Steven Souza Jr. leave their 3-1 loss to the Mets at Citi Field after aggravating his right pectoral muscle on a throw.
Souza will undergo an MRI on Saturday and be re-evaluated.
Souza sustained a strained right pectoral muscle on March 21 when he dove for a ball in the outfield. The injury kept him on the disabled list until May 3.
On Friday, after fielding Michael Conforto's single in the fifth, Souza reverse pivoted and threw toward the infield. That's when he said he felt something in his pec.
"Just frustrating, obviously," Souza said. "I don't know any other way to put it. I turned around and threw to [second baseman Daniel Descalso], and it just kind of fired up again."
Souza said the discomfort was nowhere near what he experienced this spring, but hesitated to speculate on the seriousness.

"I got some information, and the medical team recommended just for precautionary reasons we should get him off the field and remove him from the diamond," D-backs manager Torey Lovullo said. "He felt like he could still hit. His throwing was kind of an issue, unfortunately."
The D-backs acquired Souza from the Rays as part of a three-team deal that included the Yankees this spring, and they were hoping he could help replace some of the offense they lost when J.D. Martinez departed via free agency.
Souza has struggled to find his timing at the plate since missing the season's first month, hitting .167 in his first 42 at-bats so far this year.