Kansas City, Mo. ? The youngest player in the major leagues is making things look easy.

After throwing seven shutout innings and lowering his ERA to 1.73 in a 4-2 victory over Montreal, Kansas City’s precocious 20-year-old said he didn’t even have his best stuff.

“Pitching against the best hitters in the world is not easy,” he said. “I don’t know how I’m making it look.”

Greinke gave up three soft singles, struck out five and walked none in earning his first major-league win.

“Guys like him come to the big leagues probably every 10 or 15 years,” manager Tony Pena said. “This is a 20-year-old kid, and he pitches like a veteran, like he’s been in the big leagues for 10 years. The way he varies his fastball reminds me of Tom Seaver.”

Carlos Beltran had a two-run home run, and Benito Santiago drove in two runs in the matchup between the worst teams in each league.

Greinke (1-1) easily could be 4-0 after giving up just five earned runs in four starts. The bullpen blew a ninth-inning lead in his debut on May 22 at Oakland, then he had a no-decision despite allowing only one run against Minnesota in seven innings. He went seven innings in his next start at Detroit, but lost 2-0.

“I would say I did pretty good today,” he said. “But I felt better in my other starts. Pitching-wise this might have been my best. But I didn’t feel good out there. But everything went pretty good.”

The bullpen, in fact, almost blew this one. After getting two quick outs in the ninth, Jeremy Affeldt gave up two runs and had the bases loaded before Endy Chavez, who had three singles, flied out to left.

Jamey Carroll had an RBI single and Brad Wilkerson drew a walk after Affeldt loaded the bases on a double and a walk.

“That was a nightmare,” said Affeldt, who got his seventh save in eight opportunities. “Last time I went in for Greinke, I blew it. It’s on my mind, ‘Oh, don’t blow this one, too.’ Thank God I didn’t.”

Wielding a baffling array of sharp breaking pitches and tantalizing off-speed stuff, Greinke kept the Expos off balance all night.

Tony Armas Jr. (0-1), making his second start since undergoing labrum surgery on May 23, 2003, allowed three runs on four hits in five innings, with three walks and three strikeouts.

Beltran snapped an 0-for-10 slump with a homer in the third. Tony Graffanino drew his second walk of the game just ahead of Beltran’s 12th homer.

Joe Randa tripled into the right-field corner to lead off the second inning, with the ball bouncing off the wall when Terrmel Sledge made a poorly timed jump. Santiago’s grounder to deep short gave the Royals the run. Santiago added an RBI double in the eighth.

Chavez had three hits and made a great defensive play in right-center, robbing Desi Relaford of an RBI and extra bases with a diving catch of his two-out drive in the fourth. Chavez made another spectacular play in the eighth, leaping over the fence to rob Matt Stairs of a homer.

Notes: 1B Ken Harvey took the night off to let his aching muscles rest following Sunday’s violent collision with RHP Jason Grimsley. Harvey, hitting .375, was expected back on Wednesday. Grimsley was day-to-day. … The Royals hoped to have first-round draft pick Billy Butler, a high school third baseman from Jacksonville, Fla., under contract by Wednesday. … Robinson has chosen Chad Cordero to replace Rocky Biddle as his closer. … SS Orlando Cabrera and LF Brad Wilkerson collided in the first inning chasing Stairs’ high popup. Cabrera held on to the ball for the inning-ending out and both players were slow to get up and leave the field. … J.C. Carter of Kansas City was declared the Royals’ 60 millionth fan when he walked through the Kauffman Stadium gate. He was given a gift package.