PORTLAND (AP) – Chad Spann belted a grand slam in the bottom of the ninth inning to lead the Portland Sea Dogs past the Trenton Thunder 5-3 Wednesday.

David Murphy led off Portland’s ninth with a single off Trenton reliever Justin Pope. After the right-hander retired the next two batters, he walked two men to load the bases. Spann belted Pope’s first pitch over the left-field wall.

Spann hit his first Double-A home run on the first pitch thrown by Pope. The victory was the first playoff walk-off home run in franchise history.

Portland took a 1-0 lead in the best-of-five playoff series in the Eastern League’s Northern Division.

Jared Sandberg also homered for the Sea Dogs. Omir Santos and Bronson Sardinha knocked doubles for Trenton.

Santos’ double was the key hit as the Thunder grabbed a 2-0 lead in the second inning. Sandberg’s solo homer made it 2-1 in the fifth. Sardinha’s RBI double sent the Thunder ahead 3-1 in the eighth.

Randy Beam (1-0) earned the win by working the final 2/3 in the top of the ninth inning. Jon Lester, who was named the Eastern League Pitcher of the Year earlier last week, hurled seven strong inning on two runs and four hits. The left-hander, who led the league in strikeouts with 163, fanned nine and walked one.

Lester retired 13 of the final 15 batters faced.

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