BOSTON -- Jonathan Heasley pumped his fist into his glove and screamed as he walked off the mound after inducing a double play to end the fifth. It was an opportunity he was not afforded in his last start, when he gave up seven runs over just four innings in a rain-soaked game against the Tigers.

But on a crisp and dry fall night at Fenway Park, Heasley had one of the best outings of his young career in the Royals’ 2-1 series-opening loss to the Red Sox. Heasley, who left in the seventh after 83 pitches, became the first Royals pitcher to go 6 2/3 or more scoreless innings at Fenway since Kevin Appier threw a complete-game shutout at the park on May 5, 1997.

“Best start we've seen from him in the big leagues without a doubt,” manager Mike Matheny said of the 25-year-old righty. “He was attacking with everything. It was the best bite we've seen with the breaking ball. Changeup was plus … . His base was good, his timing was right. Everything was right how we wanted it to be. You couldn't ask him to do any more than what he did.”

Heasley worked quickly in his first outing at the historic ballpark, setting the tone for a two-hour and thirty eight-minute game. After allowing a single to Rafael Devers in the first, Heasley retired the next 10 batters he faced. The Red Sox didn’t get their second baserunner of the night until Alex Verdugo’s leadoff walk in the fifth.

“I thought it was a pretty good outing,” Heasley said. “I feel like I attacked the zone pretty well, commanded the zone well. The first inning was kind of out of my mechanics a little bit, just felt like I was kind of amped up, the atmosphere was kind of just a cool environment. So I kind of had to take a deep breath there and kind of slow things down a little bit. And after that, I felt like I was executing much better and had better command of the fastball for sure.”

The highlight of Heasley’s night came in the fifth inning, when he got his first taste of the storied Fenway Faithful crowd. With the bases loaded and Kiké Hernández at the plate, Heasley battled through a seven-pitch at-bat before getting Hernández to ground into an inning-ending double play.

“That was huge,” Heasley said. “Just that situation, that was probably one of the coolest environments I've been in, in my young career.”

Despite finishing with a strong line (6 2/3 scoreless innings, two hits, three walks and five strikeouts), Heasley’s velocity was down across the board. He threw 29 fastballs, with his average mph dipping 1.9 -- 91.7 on Friday compared to his yearly average of 93.6. His slider (13 pitches) saw the biggest decline, down from his 86.3 mph yearly average to 83.1 on Friday.

“I hope it goes down next time,” Matheny quipped. “There's something to that too when you try to overthrow and you sacrifice some location. So sometimes velocity, it’s overrated. Especially when you're able to keep them off balance with their spin and with the change and then moving the fastball around up and down and in and out. It's exactly what he needs to do.”

Heasley chalked up the downtick in velocity to end of the year fatigue.

“Everything felt good,” Heasley said. “I felt like it was coming out well, felt like it was getting a good ride and everything it usually has. So I wasn't worried about it, just out there executing pitches and getting outs.”

Salvador Perez drove in the Royals’ lone run of the night on an RBI single in the sixth inning. Kansas City went 1-for-5 with runners in scoring position, leaving six men on base. Perez’s single gave the Royals their first lead of the road trip after they were swept in three games in Minnesota.

Kansas City carried its lead into the eighth inning before Dylan Coleman and Scott Barlow combined to hand out four walks (two apiece), including a game-tying free pass to Verdugo allowed by Barlow. The frustrating inning included a couple of close calls by home-plate umpire Ramon De Jesus that the Royals would have liked to see go the other way.

“Not much you can do,” Barlow said. “Try to make a better pitch next pitch. Stinks at the time, but … it’s baseball. You wish it can go your way all the time, but tonight was just not that night.”