Showalter, speaking to reporters Tuesday, characterized the results of McNeil's MRI as "good news" but did not specify what the test revealed. McNeil said he got on the team bus after having the MRI and didn't talk to the doctors, but was told the test showed "not much -- nothing."
"I got a call from the trainer saying, 'Hey, everything looks great,'" McNeil explained, confirming the injury is of the day-to-day variety.
McNeil walked off uneasily after scoring on a wild pitch in the fourth inning of the Mets' 6-0 victory Monday and went straight to the clubhouse. He reached base in the fourth with a double that raised his batting average to a team-leading .327.
Showalter said he reminds McNeil throughout the season to alert him if anything feels off.
"He got ahead of it, felt it a little bit, and we got him out of there," Showalter said. "So hopefully that precaution will get him back here hopefully shortly."
McNeil did not play in Tuesday night's 8-2 loss to the Astros in Houston.
In other Mets injury news, right-hander Max Scherzer, out since May 18 because of a strained left oblique, completed his first rehab start for Double-A Binghamton on Tuesday. He allowed two earned runs on three hits and recorded six strikeouts with one walk over 3⅓ innings. He threw 65 pitches.
The Associated Press contributed to this report.