Zac Gallen pitched six shutout innings and Christian Walker slugged a three-run homer to lead the Arizona Diamondbacks to a 7-0 victory over the New York Yankees on Tuesday night in Phoenix.Blaze Alexander went 2-for-3 with two runs and one RBI, and Ketel Marte went 2-for-5 with two runs as Arizona handed New York its first loss of the season. The Yankees had won their first five games for the first time since 1992.Gallen (2-0) gave up three hits and three walks and struck out six in his second career start against New York. He also blanked the Yankees on three hits over six innings in a win last September.Eugenio Suarez and Gabriel Moreno also had run-scoring singles for Arizona. Walker, Jake McCarthy and Geraldo Perdomo also had two hits apiece as the Diamondbacks racked up 12 overall.New York had three hits and only one runner reached second base — Anthony Volpe in the second inning.Nestor Cortes (0-1) allowed three runs and eight hits over five innings for New York. He struck out two and walked two.Scott McGough, Ryan Thompson and Bryce Jarvis each pitched a hitless inning of relief for the Diamondbacks.Arizona started fast against Cortes by scoring three runs in the first inning.