Martinez was recalled from Triple-A Round Rock on Monday, indicating he will likely start Tuesday's game against the Mariners.
Yu Darvish was dished to the Dodgers in a deadline deal, opening up a spot for Martinez to rejoin the major-league rotation for the time being. It's unclear whether he'll take more than one turn in the rotation; that could ultimately depend on the status of A.J. Griffin (oblique). Martinez compiled a 4.79 ERA and an unimpressive 32:15 K:BB in 11 starts (62 innings) this season before he was sent back to the minors, so it wouldn't be wise to expect much for fantasy purposes.