Salvador Perez had two homers and three RBIs to help the Royals sweep the two-game series. Brady Singer (3-4) allowed five runs — four earned — and eight hits in 5 2/3 innings.
Wil Crowe (0-4) took the loss. He gave up eight runs and eight hits in four-plus innings.
Adam Frazier, who led the National League with 40 hits in May, doubled twice for the Pirates.
Benintendi drove in the Royals’ first run with a single in the first inning.
The Pirates scored three times in the third. Singer loaded the bases with no outs on an infield single, a walk and a hit batter. An RBI single by Bryan Reynolds and sacrifice flies by Gregory Polanco and Ben Gamel knocked in the next two runs.
Kevin Newman singled and raced home when Michael Perez sent one to the wall in right-center for a double to give the Pirates a 4-1 lead in the fourth.
Perez drew the Royals to 4-3 with his 11th home run in the bottom half. Carlos Santana led off with a single. With one out, Perez launched a two-run drive into the Pirates’ bullpen in left.
Benintendi’s grand slam capped a five-run fifth. Crowe gave up a leadoff triple to Michael A. Taylor, then walked Nicky Lopez. Whit Merrifield singled in Taylor before Crowe walked Santana to load the bases. Benintendi sent his second career slam into the Royals’ bullpen.
The Pirates scored in the sixth on Frazier’s bloop double with two outs, but they left the bases loaded.
Perez’s second home run came with one out in the seventh.
Taylor’s sacrifice fly in the eighth provided the final run.
Pirates manager Derek Shelton said 3B Ke’Bryan Hayes (left wrist strain) is likely to return to the roster Thursday against Miami. Hayes has been out of the lineup since April 4.
Royals SS Adalberto Mondesi was not in the starting lineup after coming out of Monday’s game with a “tweaked” left hamstring. Kansas City manager Mike Matheny said he wouldn’t rule out an appearance by Mondesi in Tuesday’s game, but he preferred to wait until Thursday with Wednesday’s off day.
Following an off day on Wednesday, Pirates LHP Tyler Anderson (3-5, 4.63 ERA) will take the ball against the Miami Marlins. He had a bounce-back performance against the Cubs, allowing two earned runs in five innings.
The Royals are also off Wednesday. LHP Kris Bubic (1-0, 1.52 ERA) will face the Twins for the second straight start, this time in Kansas City on Thursday. He allowed one run and four hits over six innings in Minnesota.
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