The Boston Red Sox placed first baseman Willson Contreras on the 10-day injured list Monday due to a strained left hamstring that has been hampering him for over a month, per multiple outlets. Catcher/infielder Mickey Gasper was recalled from Triple-A Worcester to take his place.

Contreras is batting .274 with a team-leading 26 home runs in his first season with the Red Sox, ESPN reported. The severity of the injury and the expected length of his absence remain unclear, per MLB Trade Rumors.

One report noted tension between Contreras and fans at Fenway Park during an Aug. 19 game, when he drew boos for slow running and subsequently held his hand to his ear and engaged in a verbal exchange with a spectator, per Yahoo Sports. Contreras will be unavailable for the start of September as Boston heads into the stretch run.