KANSAS CITY — The Royals seemed primed to help Brad Keller celebrate on his 26th birthday with a win, but White Sox slugger Eloy Jiménez had other ideas in just his second game back after nearly four months on the injured list.

Two of the Royals’ best bullpen arms came apart in the eighth inning Tuesday night, sending the Royals to a 5-3 loss at Kauffman Stadium and snapping their six-game win streak.

After Keller delivered seven strong innings of one-run ball, lefty Jake Brentz came in with a two-run lead in the eighth and clearly had command issues from the start. A leadoff double and hit-by-pitch led to the White Sox cutting the lead to one, and Kyle Zimmer came in with two outs to try and hold it there. He intentionally walked José Abreu to face Jiménez, who was 1-for-7 so far in his first series back.

Jiménez fouled off a fastball, and then Zimmer left a slider hanging in the middle of the plate. Jiménez didn’t miss, sending a moonshot to left-center field. Zimmer watched it the whole time, hands on his hips, before striking out Gavin Sheets to end the frame. After rising to one of the Royals’ high-leverage arms in the first half of the season, Zimmer now has a 8.71 ERA in July, having allowed 10 runs in 10 1/3 innings.

The loss spoiled Keller’s stellar start. The right-hander allowed a solo homer to Sheets in the fourth but otherwise limited the White Sox to four hits and two walks with four strikeouts. In four starts this July, Keller now has a 2.28 ERA, looking much more like the pitcher he has been the past two years for the Royals. He got off to a suboptimal start in the first half, pitching to a 5.97 ERA over that time, but a mechanical fix in his delivery has him pitching like himself again. And the results are showing.

In the second inning Tuesday, Keller faced trouble with a bloop single and a walk to lead off the inning. He got out of it with a popup and two swinging strikeouts, one on a filthy slider to Brian Goodwin and the other on a fastball that Leury García swung awkwardly through.