Casas hit a solo shot in the second inning, and a two-run home run that broke a 3-3 tie in the sixth. It was the first multi-homer game in Casas' major league career.
Boston also received solo home runs from Jarren Duran and Yu Chang and a two-run homer from Justin Turner. Duran's homer came in the first inning, Chang went deep in the fifth and Turner hit his home run in the seventh.
Four of the five home runs came against Mets starter Max Scherzer (8-4), who gave up five runs on six hits in six innings. Scherzer struck out seven and walked two
Boston starter James Paxton (6-2) limited the Mets to three runs (two earned) on three hits in six innings. He recorded seven strikeouts and one walk
Boston built a 2-0 lead on home runs from Duran and Casas, but the Mets went in front by scoring three runs in the fourth. Francisco Lindor and Pete Alonso scored on Jeff McNeil's two-out single, and McNeil came around to score on the play when catcher Jorge Alfaro threw the ball into center field attempting to throw him out at second
Chang's home run tied the game in the fifth before Casas put Boston in front, 5-3, by hitting his 14th home run of the season.
Boston took an 8-3 lead in the seventh. Masataka Yoshida's RBI single drove in Duran before Turner hit his two-run homer.
The Mets, who beat the Red Sox 5-4 earlier Saturday in the conclusion of Friday's suspended game, scored three times in the ninth. Alonso tripled and scored on a Francisco Alvarez single, Mark Vientos drove in Alvarez with a single and Brett Baty's single scored Vientos to make it 8-6
Kenley Jansen recorded the final out to earn his 21st save.
--Field Level Media