KANSAS CITY, Mo. -- The Kansas City Royals and Colorado Rockies,both hoping to reach the postseason, open a three-game series Tuesday night at Kauffman Stadium.

The Rockies own the top spot in the National League wild-card race by a half-game over the Arizona Diamondbacks. The Royals, who sit 1 1/2 games back of the second American League wild-card spot, are among eight teams within five games of the league's final playoff position.

Kansas City still has faint hopes of overtaking American League Central leader Cleveland after taking the final game of the series with the Indians 7-4 on Sunday. The Royals sit seven games behind the Indians.

"Huge win," said Jason Hammel, the winning pitcher Sunday.

"We needed that," Royals manager Ned Yost said.

The Royals have not fared well this year against National League clubs, losing five of nine, including being swept in a four-game series by the cross-state rival St. Louis Cardinals.

The Rockies have won eight of 14 games against American League opponents.

While Colorado is clinging to the NL wild-card lead, it lost a chance to open some ground on Milwaukee, dropping two of three at Coors Field to the Brewers. Milwaukee is four games behind the Rockies in the wild-card race.

Colorado committed three errors Sunday in an 8-4 loss to the Brewers.

"This was a great opportunity for us to jump ahead. It didn't happen," Rockies outfielder Carlos Gonzalez said. "But the good thing is -- or, I don't know if it's a good thing -- at least teams like the D-backs got swept, too. We ended up winning one game out of three, not the way you want to play at home, but it is what it is. We're still in there."

The Rockies know their only path to the postseason is a wild card. While they are in second place in the NL, they know catching the Los Angeles Dodgers is almostimpossible.

While the Rockies had a seven-game cushion for a playoff berth Aug. 9, that margin has dwindled.

Colorado will start right-hander Jon Gray (5-2, 4.74 ERA) in the series opener at Kauffman Stadium. This will be his 13th start and his 10th since coming off the disabled list June 30. He will start against Kansas City for the first time in his career.

Gray is 2-1 with a 3.23 ERA in his past five starts, allowing 11 runs, walking six and striking out 28 in 30 2/3 innings.

Gray beat the Braves on Wednesday in his latest start, allowing two runs and five hits with five strikeouts and two walks in six innings. He is 1-2 with a 6.34 ERA in seven road starts this season. He is 4-11 with a 4.93 ERA in 26 career road starts.

This will be Gray's first interleague start of the year. In five career starts against American League clubs, he is 3-0 with a 3.99 ERA.

The Royals will counter with left-hander Danny Duffy (7-8, 3.82), who was their Opening Day starter. While Duffy has a 3.14 ERA at home, he is just 3-4 this season at Kauffman Stadium.

Duffy is 0-2 with a 4.50 ERA in two career starts against the Rockies, allowing six earned runs in 12 innings. He last faced Colorado in 2014.