Top New York Mets pitching prospect Matt Harvey will be activated Tuesday and start Thursday's game against Arizona in his major league debut, the Mets announced after Sunday's game. Harvey, 23, has a 7-5 record and a 3.68 with Triple-A Buffalo this season. He gave up six runs on Saturday night, but the Mets need starting pitchers. Mets right-hander Miguel Batista was designated for assignment Sunday. The 41-year-old Batista gave up four runs in three innings on Saturday, and he's 1-3 with 4.82 ERA for the season. He was replaced on the roster by reliever Elgin Ramirez, who was called up from Class AAA Buffalo. Jeremy Hefner will start Wednesday's game.