The Mariners are expected to call up Montes from Triple-A Tacoma on Tuesday, Francys Romero of BeisbolFR.com reports.
Montes will make the leap to the big leagues after slashing .274/.369/.571 with 13 home runs and three stolen bases in 44 games since being bumped up from Double-A Arkansas to Triple-A in early July. The 21-year-old bats from the left side of the plate and has been a full-time right fielder and designated hitter in the minors this season, so he could end up occupying the strong side of a platoon with Taylor Ward, who has mustered a lowly .371 OPS since being acquired from the Orioles on Aug. 3.