KANSAS CITY, Mo. -- The Kansas City Royals are unsure whether closer Kelvin Herrera will be available Wednesday for the middle game of their three-game series against the Colorado Rockies.

Herrera exited with two outs in the ninth and the bases full of Rockies on Tuesday due to right forearm tightness. Left-hander Scott Alexander recorded the final out to seal Kansas City's 3-2 triumph and his first major league save.

"We're checking him," Royals manager Ned Yost said of Herrera. "It's in a spot … right in (his mid-forearm). It's not like in (his wrist) or in (his elbow). Kind of a spot that generally doesn't mean anything, really."

Herrera has 26 of the Royals' 28 saves this season, and the club needs him healthy and closing games as the season winds down in the chase for postseason play.

The Royals (63-61) snapped a seven-game losing streak in interleague play. They are 6-9 this year against National League opponents.

Left-hander Danny Duffy, who beat the Rockies on Tuesday for his first victory since July 26, said the day off Monday helped.

"It was nice. It was important," Duffy said. "Late in the season, off days are huge for us, especially for everyday players and the bullpen guys. Anytime you can rest, lie down and put your feet up, it's definitely a plus."

Duffy gave up just one hit, a two-run Nolan Arenado homer, and three walks over six innings.

Kansas City remains 1 1/2 games back of the Minnesota Twins for the second American League wild-card spot.

The Royals will send right-hander Ian Kennedy to the mound Tuesday. Kennedy (4-9, 5.06 ERA) is winless in his past 15 home starts, which is a franchise record. He has not won at Kauffman Stadium since Aug. 20, 2016, when he beat the Twins.

He is also looking for his first interleague victory as a Royal. He is 0-3 with a 6.00 ERA in five starts since switching back to the American League.

Kennedy is 6-7 with a 3.03 ERA in 22 career starts against Colorado.

The Rockies (68-57), who like the Royals are battling to make it into the postseason, have dropped three in a row and 10 of their past 14. The latest loss dropped them a half-game behind the Arizona Diamondbacks for the top spot in the National League wild-card standings.

Colorado has lost 22 of its past 28 road games after starting the season 24-10 in away games.

"We have to clean up some of these at-bats. It's just not good enough," Arenado said.

The Rockies will start rookie right-hander Antonio Senzatela (10-4, 4.56 ERA) on Wednesday. It will be his 19th start and 26th appearance. He last started Aug. 9 in Cleveland, pitchingfive innings of two-run ball in a no-decision.

Senzatela has made three starts and seven bullpen appearances in the second half. He threw two scoreless relief innings Thursday against the Atlanta Braves in his most recent outing.

This will be his first career start against the Royals. Senzatela is 1-1 with a 4.96 ERA in three interleague starts.