Pete Alonso hit a grand slam to power a seven-run fifth inning Monday night for the New York Mets, who rolled to a 10-4 win over the host Miami Marlins in the opener of a three-game series.Alonso’s homer was one of four by the Mets, who collected 11 hits after they were limited to just five runs on 12 hits — including one homer — in a season-opening three-game series against the Houston Astros.Starling Marte went deep in the third inning and Luis Torrens hit a two-run shot to cap the fifth-inning outburst before Brandon Nimmo closed out the Mets’ scoring with a two-run homer in the sixth.Jose Siri delivered the go-ahead hit with an RBI double three batters before Alonso chased Cal Quantrill (0-1) by lacing his fourth career grand slam — and first since May 19, 2023, when he cleared the bases against the Cleveland Guardians’ James Karinchak.Alonso and Torrens finished with two hits apiece for the Mets, who received at least one hit from all nine starters.David Peterson (1-0), who enjoyed a breakout last season, allowed two runs on five hits, including solo homers by Otto Lopez and Eric Wagaman in the first and sixth innings, respectively. He gave up three walks while striking out nine.