Syndergaard reached for his right hamstring after throwing a pitch. Mets manager Mickey Callaway and an athletic trainer came out to check on Syndergaard, who quickly walked off the field with a bit of a limp. He was later diagnosed with a strain.
Robert Gsellman entered with New York leading 8-3. St. Louis scored three runs before the inning was over.
Syndergaard threw 102 pitches.