He pinch-hit in the ninth inning and struck out in the Mets' 3-2 win over the Nationals in 14 innings.
Beltran noticed the stiffness Wednesday, but still hit a three-run drive for his first homer of the season in New York's 5-2 win over the Washington Nationals.
"I guess overnight it didn't do much better," Mets manager Willie Randolph said. "So we'll give him a day."
Angel Pagan replaced Beltran in center field and Brady Clark got the start in left for the finale of New York's three-game series against Washington. Carlos Delgado batted fourth and Pagan hit fifth in the lineup for the first time this season.
Beltran is batting .289 with one homer and seven RBIs in 13 games this season. He took batting practice before the game and said he would be fine.