BOSTON (AP) — Boston Red Sox lefthander Drew Pomeranz left Friday night's game against the New York Yankees in the middle of a batter with back spasms.

With a light rain falling most of the early innings, Pomeranz pulled up after throwing his second pitch to Chase Headley in the fourth. After talking with manager John Farrell and the training staff, Brandon Workman was called in from the bullpen to relieve him.

Pomeranz was 12-4 with a 3.39 ERA entering the game. He had won six straight decisions and hadn't lost since June 11.

He left with a 2-0 lead but was charged with the one-out walk to Headley. Workman finished the inning without allowing a run.

The Red Sox entered the three-game series against the rival Yankees with a four-game lead in the AL East.