Rookie Jackson Merrill singled home two runs during a six-run fifth inning as the visiting San Diego Padres opened a three-game series against the Milwaukee Brewers with a 7-3 win on Monday.San Diego starter Joe Musgrove (2-2) allowed three runs on seven hits over six innings. He walked four and struck out three.The Brewers loaded the bases with two outs in the ninth before Robert Suarez retired Sal Frelick on a fly ball to left field for his sixth save.Merrill, who had three hits with a stolen base, is 9-for-17 over his last four games for San Diego, which has won four of its past five. Manny Machado and Luis Campusano each contributed two hits and an RBI.Jackson Chourio went 2-for-4 with a two-run homer and a stolen base for Milwaukee, which was held to three singles in the final six innings. William Contreras extended his hitting streak to 11 games with two singles.The Padres trailed 3-1 before chasing Milwaukee starter Joe Ross (1-1) with six runs on six singles, a walk, a catcher’s interference and a passed ball in the fifth inning.Ross allowed three consecutive singles to begin the inning before Campusano scored on Fernando Tatis Jr.’s groundout. The Padres tied the game 3-3 when Tyler Wade scored on a passed ball, then moved ahead on Machado’s RBI single after Jake Cronenworth reached base on catcher’s interference.Merrill delivered a two-run single to put the Padres ahead 6-3, and Campusano followed with an RBI singled to left field, ending Ross’ outing.