Art Nathan s not waiting around for Garden chairman James Dolan to issue Isiah Thomas a pink slip.

Nathan, a 67-year-old Freeport (L.I.) dentist and lifelong Knicks fan, is taking the matter into his own hands. Wednesday, a mere half-court heave from the Garden entrance, Nathan will kick-start what he hopes will be the beginning of the end of Thomas’ Knick tenure, complete with what Nathan calls “the world’s largest pink slip” at eight-by-four feet.

“This is ridiculous what’s going on with the Knicks,” Nathan told the Daily News Tuesday. “I’m rallying the troops to do what we have to do.”

Nathan is asking all faithful Knick supporters to come out at 11 a.m. sharp today, where he will proudly display his Patrick Ewing-sized pink slip on Seventh Ave., between 31st and 32nd Streets. Nathan said he has received police permission to stage the protest there in a cordoned-off area. He has chosen that time of day to try to get more people to attend and minimize the chances of the Knicks interfering.

The massive billboard has a letter inscribed on the front, imploring Dolan to terminate Thomas immediately.

“We are fed up with the performance of your team under the leadership of Coach Isiah Thomas,” the letter reads. Below is ample space for petitioners’ signatures.

Nathan had the sign made at Sign-A-Rama in Hicksville, L.I. The store’s co-owner, 45-year-old Vinny Marino, said Nathan’s pink slip was certainly one of the strangest requests he has received. Marino, a huge Jets fan, chuckled when asked if it’s too early to draw up a massive pink slip for Jets coach Eric Mangini.

The Knicks (7-17) play host to LeBron James and the Cavaliers 81/2 hours after the start of the protest. Nathan, a season ticket-holder, will not be in attendance.

“When you think of all the great Knicks coaches - Joe Lapchick, Red Holzman - you don’t think of Isiah Thomas,” said Nathan, who said he caught several Knick games at the old Garden as a kid. “The saddest thing for me was when the Dodgers left Brooklyn. This is the second saddest thing for me. Somebody’s got to step up and do something if Dolan won’t.”

(SOURCE: DAILYNEWS.COM)