KANSAS CITY -- In the top of the eighth inning on Sunday, it looked like the Nationals were on their way to a three-game series sweep for the first time in nearly two years. They were up by one run thanks largely to a dominant start by left-hander MacKenzie Gore, and they had runners on second and third with nobody out.

But just when it looked like Washington would have plenty to smile about on its early evening flight to Los Angeles, the wheels came off over the final two innings and the Royals rallied to hand the Nats a 3-2 loss on Michael Massey’s walk-off RBI single.

So much for those visions of a three-game series sweep for the first time since June 14-16, 2021, against the Pirates. The Nationals squandered a golden opportunity for tack-on runs in the eighth against reliever Aroldis Chapman, then saw Chad Kuhl surrender a game-tying homer to left-fielder Edward Olivares in the bottom of the inning.

In the bottom of the ninth, Kuhl was betrayed by the defense as the Royals walked it off. With one out, MJ Melendez hit a grounder that rolled through the legs of first baseman Dominic Smith for a two-base error. Then, with two outs, Michael Massey smacked a liner to right that Lane Thomas chose to play on a hop rather than attempting a diving catch. The throw home by Thomas was considerably late, and the Nats left the field knowing they had missed a big opportunity for a series sweep.

“It was a tough one, kind of top-spinning at me,” Thomas said. “Looking back, I probably should have dove. The ball got on me quick. I wish I could have made a better play at home. It was one of those in-between plays where if you dive and miss it, the game is over. I just thought I might have a chance to throw him out.”

Manager Dave Martinez said a diving attempt would have been the right play in that situation.

“That last play is a do-or-die play,” Martinez said. “You can’t have the ball bounce in front of you like that. You’ve got to try and come catch it. If it’s by you, it’s by you and the game is over anyway. I thought [Thomas] thought maybe he could throw the guy out, but you’ve just got to come get the ball.”

Despite the sting of a tough loss, Washington was excited by Gore’s bounce-back performance. After throwing 103 pitches (60 strikes) over 4 2/3 innings in his start against San Diego last Tuesday, Gore tallied a career-high 11 strikeouts while equaling a career high by going seven innings on 106 pitches (75 strikes) Sunday.

Gore allowed just three hits and walked one. His only blemish was a solo homer that he surrendered to Melendez in the seventh. The 24-year-old left-hander finished his outing with a flourish after the Melendez homer, striking out the next two batters and leaving with a 2-1 lead.

“It was good,” Gore said. “We got left-handers out better. We had four days to work on it.”

Martinez said the key for Gore was keeping his fastball down.

“I talk about him attacking the zone,” Martinez said. “Everything plays off the ball that’s down, and he threw the ball down really well today. He was tough. Great outing by him. It stinks that he couldn’t get the win there.”

The Nationals went 2-for-12 with runners in scoring position and left 11 men on base. Meanwhile, they had some high leverage relievers unavailable and Kuhl -- who had shined in the series opener Friday, getting five outs to earn his first career save -- was called on to protect a one-run lead.

The 452-foot homer from Olivares gave Kansas City new-found energy, and Washington couldn’t regain any late-inning momentum.

“We had opportunities but just couldn’t capitalize today,” Martinez said. “When you do that, you leave the door wide open for these things to happen."