HIDEKI Matsui has played his time as a Yankee ideally. He has fit into an accomplished clubhouse by acting with humility. He has endeared himself with foreign and local media by being accessible and pleasant.

But to truly become a Yankee, more is needed. You must rise to the challenge of New York, the team’s history and performing under great scrutiny. Jason Giambi, for example, accepted $120M from George Steinbrenner, but really became a Yankee when he hit a walk-off, bottom-of-the-14th grand slam against the Twins on a rainy night last May. Yesterday – on a cold, gray afternoon against, yes, the Twins – Hideki Matsui officially earned his pinstripes, fittingly on the first day he wore them for real.

In a home opener with so much scripted from the first pitches thrown by Yogi Berra and Whitey Ford to Challenger the bald eagle flying in from center field, Matsui provided a theatric moment too corny for a script. With his new home crowd chanting his last name, Matsui launched a fifth-inning grand slam well into the right-field bleachers that proved decisive in the Yankees’ 7-3 win.

“When I look back, I may say this was the moment that made me feel comfortable as a member of the Yankees,” Matsui said.

Never has a first homer been timelier for a man who already had 332 professional homers. On the season-opening road trip, Matsui had a hit in all six games, played excellent defense and ran the bases expertly. But he had come from the Far East as Godzilla, the great homer hitter of Japan. And in Week 1 he was more Punch and Judy than long and gone. A continued power outage would have elevated the already steep pressure on Matsui in both New York and from back home where Matsui is nothing less than a national treasure.

“[The grand slam] certainly adds to my confidence in playing here,” Matsui said. “Now fans will remember my name.”

Actually, a crowd of 33,109, that included Matsui’s parents and brother, proved they knew his name before the homer. With the Yanks leading 3-1 in the fifth, Twins manager Ron Gardenhire opted to walk Bernie Williams with one out and second and third to load the bases. Boos for putting Williams on melded into a standing ovation to encourage Matsui. And that quickly became chants of “Mat-sui, Mat-sui.”

In the Yankee dugout, Robin Ventura turned to Roger Clemens and said, “By walking Bernie they are going to make a huge star out of this guy.” With the count 1-1, the chants came again, just louder. Matsui took a ball and dribbled a grounder foul. Now, the fans rose, their pleas for success growing in noise and anxiety. Ball three, the count was full.

It was 5:48 p.m. – 6:48 a.m. Wednesday in Japan. Twins starter Joe Mays tried a changeup and Matsui hit a drive with such force – “a bomb,” according to first base coach Lee Mazzilli – that right fielder Michael Cuddyer took just a few halting steps. Matsui would say, “It felt like I didn’t hit it on my own. It felt like I had the energies of others. The fans, being in Yankee Stadium and previous Yankees helped me out.” So on this day, he not only had the power of Godzilla, but the mystical oomph of The Natural.

Ventura looked at Clemens wordlessly with a smile. Mazzilli said, “I just got goose bumps.” Williams ventured that “they must have been jumping up and down in Japan.” The Stadium crowd took on an October noise, the stands actually gyrating. Matsui’s teammates greeted him outside the dugout and bench coach Don Zimmer encouraged Matsui to take a curtain call for the still roaring fans.

“It was the story of the game,” Ventura said. “It was perfect.” For Matsui, who came here amid great hype and a greater hope from an entire country, it was a grand opening.