Pete Alonso lofted the walk-off sacrifice fly Monday night for the New York Mets, who edged the Pittsburgh Pirates 4-3 in the opener of a three-game series.David Bednar (0-4) struck out Luisangel Acuna to open the ninth before Francisco Lindor’s routine grounder behind second base skipped under the glove of shortstop Isiah Kiner-Falefa. Lindor went to third when Soto singled to right-center on the next pitch and scored easily on Alonso’s fly out to deep right.The walk-off win was the fourth of the season for the Mets. Alonso collected the eighth walk-off RBI of his career.Huascar Brazoban (2-0) earned the win despite blowing the save in the ninth, of the Pirates tied the score via a single, an error by Lindor and a bunt before Ke’Bryan Hayes had the game-tying RBI infield single.Jeff McNeil laced an RBI double in the fourth for the Mets, who have won five of seven. Juan Soto tied the game with a run-scoring groundout in the seventh, one batter before Acuna scored from second on Alonso’s infield single.Lindor and Mark Vientos had two hits each for the Mets.