KANSAS CITY, Mo. -- Daniel Nava came down with a case of food poisoning shortly after the Boston Red Sox hit town Wednesday night.

Now he's made Kansas City sick.

Batting left-handed against Aaron Crow in the sixth inning, Nava drove the right-hander's first offering to him into the visitors bullpen behind right field. His second career grand slam and Boston's fifth of the season put the Red Sox up 7-4. They went on to win 8-4, taking three out of four from the frustrated AL Central-contending Royals.

Nava declined to say what exactly made him sick earlier in the series. It was something he ate at a Kansas City hotel.

"Food poisoning is no fun, that's for sure," he said. "But to come out with the win overall in the series is big for us. I wasn't feeling well, but we had a lot of guys who either weren't feeling well or were banged up. We're just trying to get out there and be competitive, and we certainly were a little more than that."

Kansas City fans are not feeling well either. The Royals started this series with a one-game lead over Detroit in the AL Central and ended it with a deficit of a game and a half.

But Red Sox manager John Farrell was blunt when asked if he felt sorry for the long-suffering franchise that's trying to snap a 28-year playoff drought.

"No," he said. "I mean, we're all competitors. Everyone in the game knows it's been a long time since they've been in the postseason. They've got a good team. But our season's not over and certainly we're going to play up to our capabilities and with the competitiveness we expect out of our guys."

Several Sox players were competitive in this one.

The Red Sox were trailing 4-0 in the third when red-hot rookie shortstop Xander Bogaerts lined a three-run shot off Jason Vargas to make it 4-3.

Then in the sixth, Nava, known for taking a cautious approach at the plate, wasted no time going after Crow. In fact, the switch-hitter was happy to see Royals manager Ned Yost not replace his righty reliever with a lefty. Nava's average from the left side of the plate is about 130 points higher than from the right.

"I looked up in the bullpen and if they were going to a lefty, they would have had him up, and they didn't have him up, so I knew I was going to be facing a righty," Nava said. "It was just a matter of whether I was going to get a pitch to hit or not, and fortunately I did."

Farrell does all he can to keep Nava facing right-handers.

"We were fortunate. We got him on the left side of the plate in that situation, having him sandwiched between two right-handers," Farrell said. "They make a move to the bullpen, you get Vargas out of the game, and it kind of set up good for us. In certain situations, he has such a reputation as a patient hitter. He has a willingness to go first pitch and that was the case today."

Farrell did not question his Kansas City counterpart's thinking.

"I don't know what goes into their decisions. But we put him between right-handers to keep him on the left side of the plate, and it worked out," he said.

Bogaerts also had a sacrifice fly for a career-high four RBIs while writing his name into the Kansas City record book, although it is admittedly a very small entry. At 21 years and 348 days, he's now the youngest Red Sox player ever to homer off the Royals in Kansas City.

Bogaerts had three hits in four at-bats while his 21-year-old rookie partner at second base, Mookie Betts, was 2-for-4.

Betts has multiple hits in nine of his last 17 games.

"What he and Mookie are doing at the top of the order has been impressive," Farrell said. "For the age that they are, the stage of the career that they are, it's very impressive to see two young guys of that age performing like they are, as consistently as they are. Mookie with some excellent base running. But those two guys are doing an excellent job."