KANSAS CITY — As Danny Duffy mowed down the Rays’ lineup in the early part of Monday night’s series opener at Kauffman Stadium, he was on a milestone watch. The veteran lefty was nearing 1,000 career strikeouts as a Royal — the only team he’s ever played for — and the achievement came in the fourth inning.

After throwing three consecutive balls to Manuel Margot, Duffy hit the top of the zone and the bottom for two called strikes before getting Margot to swing through a high-and-tight fastball for the inning-ending strikeout.

It was career strikeout No. 1,000 for Duffy, who was excellent once again for the Royals despite the 4-1 loss to the Rays — all but one of Tampa Bay’s runs on miscues from Kansas City’s defense, with Carlos Santana dropping a high popup at first base and Whit Merrifield letting a grounder get by behind second base.

Duffy allowed two unearned runs, but he lowered his ERA to 0.50 with his third six-inning outing this season. He’s only allowed one earned run in 18 innings so far, and Monday night, he struck out eight with two walks. The most trouble he faced was in the sixth inning, as he neared 100 pitches and loaded the bases with a single and back-to-back walks with one out. But Royals manager Mike Matheny stayed with Duffy, and Duffy delivered.

After a ball in the dirt and two swinging strikes, Duffy got Francisco Mejía to hit a weak chopper right back to the mound. Duffy threw home to his longtime batterymate, Salvador Perez, who turned the 1-2-3 double play.