Amed Rosario gave the New York Mets a lead they’d never relinquish with a three-run homer in the second inning and finished with a career-high four RBIs Thursday night as the Mets beat the host Atlanta Braves 6-3 in the opener of a four-game series.The Mets have won two straight. The Braves saw their three-game winning streak snapped.Rosario added an RBI single in the sixth. He had four previous three-RBI games, most recently last Sept. 12 against the Miami Marlins. The 23-year-old shortstop has reached base safely in 11 of the first 12 games this season.Hot-hitting rookie Pete Alonso launched a long two-run homer in the seventh for the Mets. Alonso has six homers and 17 RBIs in his first 12 big league games. He entered Thursday as one of just seven big leaguers ever with 15 or more RBIs in his first 11 games and the first since Mark Quinn had 16 RBIs for the Kansas City Royals in 1999.Left-hander Steven Matz (1-0) finally factored into a decision after giving up two runs on four hits and one walk while striking out eight over six innings. Matz went a team-record eight starts without a decision dating back to last Sept. 1, despite producing a 2.11 ERA in those outings.Edwin Diaz, the fifth Mets pitcher in the game, surrendered two hits in the ninth but struck out two, including potential tying run Freddie Freeman for the final out, to earn his fifth save in as many opportunities.