Johan Santana arrived at Shea Stadium yesterday, put on his no. 57 Mets jersey for the first time, and said he anticipated little difficulty in adjusting to pitching before some of baseball’s most demanding fans.

“I think the game is the same,” he said. “I’m not going to let that affect what I do on the field.”

The Mets introduced Santana with a choreographed news conference, one that began with video highlights and Latin music. After an extended period for still and video cameras, and a brief statement by Santana, the Mets turned up the house lights of Shea Stadium’s Diamond Club for questions. Santana answered many with clichés, speaking how he would take things one day at a time, that success was a team effort, and that he will have to make adjustments to pitching in the National League. He understands that Mets’ fans demand a World Series championship — or at least an NL pennant — immediately following last year’s September collapse.

“Of course, it has to be this year and beyond,” he said as his wife and father looked on.

Santana walked in past a gift shop already stocked with replicas of his new jersey in home pinstripes and black, and in children’s sizes. Mets general manager Omar Minaya introduced Santana, who agreed last Friday to a $137.5 million, six-year contract that allowed his trade from the Minnesota Twins to be finalized the following day. Minaya pronounced it was the start of “a great era of Mets baseball.”

“Welcome to the city of baseball,” Minaya said.

Manager Willie Randolph, having acquired an ace for his staff, looked on from his front-row seat. “You should be happy, Willie,” Minaya said.