Yankees 8 Royals 2

When the Yankees signed Mike Mussina, every American League team’s worst nightmare is where the Royals find themselves today.

After getting dominated by Roger Clemens and Andy Pettitte in successive games to open the season, the Royals must find a way to beat Mussina at Yankee Stadium in order to avoid being swept.

If Mussina, who is making his Yankee debut, is anywhere near as sharp as Clemens was Monday and Pettitte was last night, when he coasted to an 8-2 victory in front of an announced crowd of 26,499, the Royals have no chance.

And that’s before you get to the Yankees’ lineup, which has punished Royal pitching in both games to prove spring training should never be used as a measuring stick.

Pettitte, who led the Yankees in wins with 19 last year, benefited greatly from the 8-0 cushion after two innings the Yankees grabbed off Blake Stein. In seven innings, Pettitte allowed one run, six hits, didn’t issue a walk and fanned five.

The early bulge continued a pattern of strong run support the Yankees give Pettitte, who received a healthy 6.78 runs per start a year ago.

“Sometimes I have a tendency to quit pitching and throw nothing but fastballs,” Pettitte said of working with big leads. “Georgie [Posada] did a great job of calling the game and I stayed with him.”

After proving spring training means nothing when it comes to veteran hitters – the Yankees hit a major-league low .257 under the palm trees – the Bronx Bombers have scored 15 runs in 16 innings.

David Justice’s grand slam, the fifth of his career and his first in pinstripes, upped the Yankees’ lead from 4-0 to 8-0 in the second. Bernie Williams had a two-run double to highlight a four-run first.

“It was unbelievable, the first two innings,” Justice said. “We are swinging the bats good right now and taking the pressure off our pitching staff. I was just trying to hit a base hit.”

Chuck Knoblauch, who scored two runs and swiped two bases, recorded his first outfield assist in the fourth when he threw out Carlos Beltran trying to stretch a single into a double.

Give Knoblauch high marks for a strong one-hop throw but you have to wonder what Beltran was doing since the Royals trailed 8-0 at the time he led off the inning.

Knoblauch was charged with his first error in the eighth when he bobbled Luis Ordaz’ single and allowed Ordaz to take second.

Mark Quinn ruined Pettitte’s shutout bid with a one-out solo homer in the fifth.

The Royals received a large scare in the sixth when second baseman Carlos Febles and right fielder Jermaine Dye, two keys in what is considered a strong lineup, collided chasing Williams’ fly ball down the right field line.

As Dye was making a running catch coming in, Febles’ left shoulder tagged Dye’s head. Dye held onto the ball, but both players were motionless on the ground. Eventually, they walked off the field, woozy, but without help.

Pettitte was removed after seven because of a tweaked right ankle he suffered chasing Raul Ibanez’ infield single leading off the inning.

“We took him out as a precautionary thing,” manager Joe Torre said of Pettitte, who tumbled after failing to field the slow roller. “He was great. For the first time out, he was right on tonight.”

Stein, who became a father for the first time Monday night when wife Ellen delivered Corinne Elise, had time to get back to K.C. in time for the 11 p.m. feeding since he didn’t get through the second inning.

After travel problems caused Stein to arrive at the Royals’ midtown hotel at 2 p.m., manager Tony Muser should have given the right-hander the night off. Instead, Muser watched Stein struggle with his control (six walks, one intentional) and give up eight runs and five hits in 12/3 innings.

That was a far cry from the pitcher who entered the game having allowed the Yankees two runs in 16 innings in two games across the past two years.

“He was getting behind, and when you do that, you get into trouble,” Torre said of Stein.

Knoblauch opened the game with a single to right and Stein was facing severe trouble early when Alfonso Soriano followed with a ground-rule double to left. After Stein fanned Paul O’Neill on a 1-2 pitch, Williams doubled in two runs in and Justice followed with a walk.

Tino Martinez’ single scored Williams from second but Justice was caught off third for the second out. With Martinez on third and the count 3-0 to Posada, Stein issued the fourth ball intentionally. Luis Sojo ended the rally with a grounder to third.

The beating continued in the second when Stein walked the bases loaded and watched in horror as Justice unloaded on a 1-1 pitch, sending it 12 rows deep into the right-field seats for an 8-0 bulge.