David Ortiz’s two-run homer lifted the Boston Red Sox to a 4-0 victory over the visiting Oakland Athletics on Saturday and a sweep of their marathon, rain-delayed doubleheader.

The Red Sox won the first game, which took more than six hours to complete because of a pair rain delays associated with Hurricane Irene, 9-3.

Boston opened up a two-game lead in the American League East over the New York Yankees, who had their doubleheader at Baltimore postponed because of Irene.

Alfredo Aceves (9-1) picked up the win in relief of Erik Bedard, who pitched four scoreless innings but did not return to the mound following a one-hour rain delay in the fifth. Aceves pitched three hitless innings.

Ortiz, who finished with three hits, belted his 27th homer of the season in the second to give the Red Sox a 2-0 lead.

Jarrod Saltalamacchia drove in two runs with a double in the sixth and a groundout in the fourth.

Graham Godfrey (1-2) allowed three runs on six hits in four innings.