Martinez (15-9) lost after allowing two runs on six hits and four walks with six strikeouts in six innings during Sunday's 3-1 loss to the Cubs.
Martinez allowed two runs or fewer for the seventh time in his last eight starts, but was outdueled by Jon Lester and failed to come away with the win. The 25-year-old has essentially replicated his numbers from last year, solidifying his status as one of the best young starting pitchers in baseball. He will make his final start of the year Friday against the Pirates at home.