Before this Yankees’ season, Domingo German was fighting for a spot on the roster, either in the back of the rotation or in the bullpen, and D.J. LeMahieu was penciled in as a multiple-position infielder. They quickly became irreplaceable.

Both showed why on Saturday afternoon against the team’s limping rival, the Boston Red Sox. LeMahieu, who has been one of the Yankees’ best all-around players this season, has haunted the struggling Red Sox ace Chris Sale this season, and he did so again, smashing two home runs off him in a 9-2 victory in the first game of doubleheader sweep.

On the mound, German once again proved that he has been the ace of the Yankees’ rotation in the absence of the injured Luis Severino. Three days after the Yankees failed to complete a trade to upgrade their leaky rotation, German spun seven stout innings — the longest by a Yankees starting pitcher since C.C. Sabathia’s seven innings on July 6.

German allowed just two runs, on solo home runs by Andrew Benintendi and Jackie Bradley Jr., and struck out seven on 97 pitches. By lowering his earned run average to 3.98, he became the only Yankees starting pitcher to be below 4.00 this season. German was tied for the major league lead with 14 wins (with two losses).