The Houston Astros will call up top prospect George Springer on Wednesday after sending Robbie Grossman down to make room, reports CBS Sports.
Lucas Harrell is also set to be designated for assignment in what is believed to be a corresponding move.
Springer, an outfielder, hit a grand slam on Tuesday to take his season figures to 15-for-47 (.319) with three doubles, two home runs and five stolen bases in 12 Triple-A games.
His 2013 season in the minors finished with figures of 303/.411/.600 with 37 home runs and 45 stolen bases, inspiring Baseball America to name him the 18th best prospect in the game.
As Springer has spent over two weeks in the minors, his free agency will be pushed back one-year, taking his eligibility from 2019 to 2020.
Springer hit headlines in the off-season after rejecting a $23 million, seven-year extension despite the fact it was an unprecedented offer for someone with no major league experience.
Grossman, 24, is hitting .125/.236/.313 so far this season while Harrell allowed four runs in five innings on Tuesday, taking his ERA up to 9.49 for the season.