PORTLAND — The New Hampshire Fisher Cats (62-63) jumped out to a 5-0 lead and held on to defeat the Portland Sea Dogs (47-81), 8-4 in the Eastern League series opener on Monday night at Hadlock Field.

New Hampshire put up five runs on Sea Dogs starter Justin Haley (5-14), who suffered the loss. The Fisher Cats scored twice in the fourth and three times in the sixth to take a 5-0 lead. Haley allowed five earned runs on five hits in five-plus innings while walking two and striking out five.

Dwight Smith Jr. went 2-for-4 with a pair of doubles, three runs scored and a walk for New Hampshire. Melky Mesa finished 3-for-5 with two runs scored and an RBI.

Conner Greene (2-0) earned the win for the Fisher Cats in his third Double-A start. Green had only allowed one baserunner through the first five innings before he ran into trouble in the sixth, allowing four runs on three hits. He finished the game allowing four runs (three earned) on four hits in 5 1-3 innings. John Anderson and Gregory Infante (first save) combined to hold the Sea Dogs scoreless over the last 3 2-3 innings.

Manuel Margot, Tzu-Wei Lin and Sam Travis each had RBIs in the sixth inning for the Sea Dogs, while Travis later scored on an error by Jorge Flores.

The Fisher Cats responded with three unanswered runs to extend their lead to 8-4.

The series continues tonight at 7 p.m. as Portland’s Danny Rosenbaum (0-6, 8.14) opposes New Hampshire’s Casey Lawrence (11-12, 4.81).