New York Yankees designated hitter Alex Rodriguez did not finish Tuesday's game against the Baltimore Orioles after clutching his right hamstring while running the bases in the fifth inning.
After the 4-1 loss, the Yankees' sixth in a row, manager Joe Girardi said Rodriguez will undergo an MRI on Wednesday to determine the severity of the injury.
But he did not sound optimistic, saying it is "definitely worrisome".
Rodriguez, 40, missed two games with an oblique injury earlier in the season.
That injury caused Girardi to express concern as well, but it turned out to be minor.
Rodriguez, who entered Tuesday's game batting just .203 with five home runs and 12 RBIs, is earning $21million this season and is set to make $21m more next year, the final year of his 10-year, $275m contract.