Berti, who hit for the cycle on Tuesday night, completed three-fourths of the rare feat on Thursday night to lead the New Hampshire Fisher Cats past the Portland Sea Dogs 4-2 at Hadlock Field.
The victory, coupled with Trenton's loss on Thursday, enabled the Fisher Cats to break from a tie and take a one-game lead over the Thunder in the Eastern League's East Division.
New Hampshire has four regular-season games remaining, a four-game series against the Hartford Yard Goats starting tonight at Northeast Delta Dental Stadium.
On Thursday, Berti doubled in the first inning, singled in the second, grounded out in the fourth, tripled in the seventh and walked in the eighth.
Bo Bichette also had a big night, collecting three singles and two runs batted in. One of those hits knocked in the winning run in the seventh inning; Bichette then scored an insurance run on Harold Ramirez' double.