BOSTON -- Rubby De La Rosa quietly walked up behind reporters waiting for him and went unnoticed before he got their attention.
His actions are much louder on the Fenway Park mound.
"He's been outstanding at home," Boston manager John Farrell said. "Even in the couple of situations where we gave an extra baserunner, he shut it down and pitched with a lot of poise tonight."
Mike Napoli hit a tiebreaking homer, sending the defending World Series champions to their sixth win in seven games. Boston is looking to climb back into the race from the AL East's basement.
Kansas City's Eric Hosmer extended his career-best hitting streak to 15 games with a single. The Royals lost for the eighth time in 11 games, falling to 10-20 in one-run games after leading the AL with 31 victories last season.
Napoli's homer cleared a billboard atop the Green Monster seats and completely left the park in the sixth.
De La Rosa (3-2) gave up one run on five hits, walking four and striking out two. He worked out of trouble most of his outing.
"It's fun to pitch here," he said. "I feel comfortable here at Fenway. I like the mound. I like the fans. I feel comfortable here."
Danny Duffy (5-10) allowed two runs -- one earned -- on six hits in 6⅔ innings. It was his fifth loss in six starts, but he's allowed two or fewer runs in four of the losses.
"We're not scoring enough runs. It's as simple as that," Royals manager Ned Yost said of the one-run losses. "When we score, we win. Our bullpen does a nice job of holding it close. It's a combination of not capitalizing on opportunities, and we had opportunities tonight, a couple of them."
The Royals have scored four total runs, and not more than one in any of Duffy's past five losses.
"I don't even think about it that way," he said. "These guys in here got my back day in and day out."
In two of his three home starts, De La Rosa pitched seven shutout innings. In his last one, he gave up three runs in five innings.
De La Rosa stranded runners at second base in four of the first six innings, twice also leaving a runner on first.
"I didn't try to think about me on base," he said, flashing a quick smile. "I try to think about the next hitter."
Infante's fielding error allowed Boston's tying run in the fourth. With runners on first and second, Infante had Shane Victorino's probable inning-ending, double-play grounder go right through his legs, scoring Napoli.
Boston left fielder Jonny Gomes bumped into shortstop Brock Holt, dropping a ball for a two-base error in the fourth, and called off Holt, but had the ball fall in front of him for a double in the fifth.
Boston's past eight home wins have all been by one run. ... The Red Sox activated RF Victorino from the 15-day DL before the game and optioned OF/INF Mookie Betts to Pawtucket. Victorino, who had been on the DL since May 24 with a strained right hamstring, got a nice ovation before his first at-bat, and went 1-for-3. ... The Royals started Dyson in CF in place of slumping Lorenzo Cain, who is hitless in his past 19 at-bats. "The off days definitely help him, coming off the three days at Tampa on the turf really beat up his legs," Yost said of Cain. "If I could do it the day I wanted, we'd give him the day off tomorrow, but there's a lefty going tomorrow." ... Boston sends LHP Jon Lester (9-7, 2.65 ERA) against RHP Yordano Ventura (7-7, 3.22) in the series finale Sunday. Lester has a 6-3 mark with a 1.60 ERA in 10 career starts against Kansas City. ... Actor Steve Carell of "The Office" was in the stands, wearing a Red Sox T-shirt.