KANSAS CITY, Mo. -- The Kansas City Royals rotation continues to give up nothing.

Chris Young extended the Kansas City starters' scoreless inning streak and designated hitter Kendrys Morales drove in all the runs with two homers as the Royals downed the St. Louis Cardinals 5-0 on Friday night.

Young (4-0), who lowered his ERA to 0.78, pitched six innings and gave up six hits and two walks with two strikeouts to pick up the victory.

"He wasn't as sharp as he's been, but they still couldn't score off him," Royals manager Ned Yost said. "Just his ability to get through six innings scoreless was impressive."

Royals starters have not allowed a run in the past four games spanning 26 innings.

The game matched the teams with the best records in their respective leagues. The Royals have won four straight and at 27-14 have the best record in the big leagues. The Cardinals have failed to score in two straight games.

Morales and catcher Salvador Perez each had three hits for the Royals.

Kansas City left-hander Franklin Morales and right-handers Ryan Madson and Jason Frasor worked the final three innings to complete the shutout.

Madson wiggled out of a bases-loaded jam in the eighth. Frasor had runners at second and third with one out in the ninth but struck out designated hitter Matt Holliday and retired first baseman Matt Adams to preserve the shutout.

Morales hit a three-run homer with two outs in the first inning and blasted a two-run shot in the third, bringing his RBI total to an American League-leading 37.

After shortstop Alcides Escobar walked and center fielder Lorenzo Cain singled, Morales picked on a 2-2, 93 mph fastball from Lance Lynn and drove it over the right-field wall, an estimated 404 feet.

Morales duplicated the feat in the third after Cain singled. Morales ripped an 88 mph slider from Lynn over the Cardinals' bullpen, estimated at 418 feet, to hoist the Royals' lead to 5-0.

"I made two mistakes," Lynn said. "Those balls they were fouling off where they were making weak contact (early in the game) they started putting them in play with weak contact."

It was Morales' 13th career two-homer game. His last previous one came Sept. 5 against Texas while with the Seattle Mariners.

"It's nice to have a guy you can count on in the middle of your lineup," Yost said. "If you make a mistake, he can hit the ball a long way as evidenced by tonight.

Young, who was making his fourth start after beginning the season in the bullpen, gave up six singles and walked two in six innings, but yielded no runs while stranding seven runners.

"I wasn't great tonight," Young said. "I wasn't as sharp as I would like to be. They fouled off some tough pitches. I had to really work. They made me work for everything.

"There were some hairy moments there and fortunately I was able to get out of them."

The Cardinals stranded 13 runners.

"I don't think they were too happy with not putting something on the board," Cardinals manager Mike Matheny said. "Nobody wants strikeouts and popups."

NOTES: Royals LHP Danny Duffy, who has a 13.03 ERA in his past three starts, was scratched from his Saturday start with a sore shoulder. RHP Edinson Volquez will move up a day and take Duffy's spot. ... Royals LHP Jarson Vargas threw a 45-pitch, three-inning simulated game. He is on the disabled list with a flexor strain. ... Whitey Herzog, 83, who managed both the Royals and Cardinals, was given a resounding ovation when introduced on the field before the game. ... Cardinals RHP John Lackey, who starts Saturday, is 3-4 with a 3.54 ERA in 10 starts against the Royals. ... 2B Kolten Wong batted leadoff for the Cards for only the sixth time. He singled and walked twice.