CHICAGO -- With his pitch count nearing 100, Royals starter Cole Ragans knew the sixth inning would be his last on Friday against the Cubs.

And with Kansas City holding a one-run lead, Ragans made sure it stayed that way.

“I emptied the tank right there and gave it everything I had,” Ragans said after the Royals’ 4-3 series-opening win at Wrigley Field.

After Yan Gomes greeted him with a first-pitch leadoff single, Ragans struck out the next three batters in the sixth -- Seiya Suzuki, Jeimer Candelario and Patrick Wisdom -- to put a bow on another strong performance.

Ragans tossed six innings, working around eight hits and two walks to hold the Cubs to three runs. He struck out nine, two shy of the career high he set 11 days ago in his start at Fenway Park against the Red Sox.

Ragans, whom the Royals acquired from the Rangers in the Aroldis Chapman trade, has 36 strikeouts through five outings with Kansas City. It’s the most strikeouts to begin a Royals career through five outings; James Shields (32 strikeouts in 2013) previously held the record.

Whether the lefty was feeling any signs of fatigue later in Friday’s outing, he didn’t show it. Ragans’ strikeout of Wisdom to end the sixth came on a 98.4 mph four-seam fastball -- the second hardest of the 106 pitches he threw.

“He really stepped up,” Royals manager Matt Quatraro said. “That sixth inning was an enormous inning in the game, for him to go out and punch out the side there.

“I think early in the game, he was a little bit off with his command, and then he settled in. His stuff was electric again.”

Ragans walked Cubs leadoff man Christopher Morel on five pitches in the first inning, and Nico Hoerner followed with a single. But Ragans bounced back to retire the heart of the Cubs’ lineup -- Ian Happ, Cody Bellinger and Dansby Swanson -- to get out of the inning unscathed.

He didn’t waver after the Cubs tagged him for three runs and five hits in the fourth inning. Ragans retired the side in order in the fifth, striking out Happ and Swanson in the process.

“He had a good feel for a lot of different pitches today while throwing 98,” Hoerner said. “And kind of using that sparingly, but obviously that’s in your head as a hitter.

“He had a good mix. I felt like we still had some chances, and the three runs could have been four or five and it’s a different game.”

Ragans recorded four strikeouts with his slider, three with his four-seamer and two on his changeup. He threw his changeup 31 times and got 21 swings, including seven whiffs.

“He’s been fun to watch,” outfielder Drew Waters said. “Not many lefties throw 99 [mph]. Just getting the opportunity to play behind him and not only see the velocity, but also the breaking pitches he has to offer, it’s impressive.”

Ragans has been on quite a roll since joining the Royals last month. In five starts (28 2/3 innings), he has a 2.51 ERA, with 10 walks compared to the 36 strikeouts. In 17 relief appearances with the Rangers (24 1/3 innings), he had a 5.92 ERA, 24 strikeouts and 14 walks.

“He’s been great,” shortstop Bobby Witt Jr. said. “The stuff is electric. He’s got four or five plus pitches. It’s been fun.”

Waters and Witt also each came up big Friday. In the ninth, the Royals led 4-3 when Hoerner tried stretching a single down the right-field line into a double. Waters threw him out at second base.

Witt’s fingerprints were all over the win. He hit what appeared to be a routine ground ball in the fourth inning. Third baseman Candelario backed up to play it on a hop, and the speedy Witt beat the throw for an infield single. He later scored on a Salvador Perez sac fly.

In the sixth, Witt dropped a go-ahead two-run homer into Wrigley Field’s left-center-field basket Friday. It continued a torrid stretch for the 23-year-old, who is slashing .336/.370/.664 post-All-Star break, with 10 home runs and 31 RBIs.

Witt has hit 12 homers since July 1 (40 games), matching his total through his first 81 games this season.

“We’ve seen him doing both sides of that for a while now,” Quatraro said of Witt. “It is impressive, and there aren’t that many guys that can do it. It’s something you can’t take for granted.”