Armed with coolers of sandwiches, beer, and Bloody Marys, Harvard and Yale alumni from New York are planning for a mass exodus to New Haven, Conn., this weekend to attend the most significant Harvard-Yale football game in nearly four decades.

For the first time since 1968, the final weekend of the Ivy League season will pit two teams that are undefeated in the league, and for the first time in many years, the refurbished Yale Bowl is expected to sell out all of its 61,446 seats.

Many older alumni say they will don their raccoon coats for lavish tailgate parties serving lobster and champagne, while younger Yale alumni from the classes of 2004, 2005, and 2006 are sponsoring a Dunkin Donuts v. Krispy Kreme showdown and advertising “a big grill and tons of BEER” behind the undergraduate tailgates in Lot D.

“We’ve got everything ready — great food, good wine and beer,” Governor Pataki, who graduated from Yale in 1967, said in a telephone interview yesterday from his Manhattan law office.

Mr. Pataki, who said he spent his own undergraduate years drinking beer and participating in politics rather than playing sports, said each year for the game weekend he hosts about 30 friends from the rival schools at his house in Garrison, N.Y., for poker and fight song sing-a-longs. “We all hang out before, but we sit on opposite sides at the game,” Mr. Pataki said. “None of us are particularly good losers.”

The Harvard-Yale football rivalry dates back to 1875, when rugby was evolving into American football. For both Harvard and Yale, beating their premiere rival is generally considered more significant than the team’s season record.

The sporting event, hosted by Yale every other year, is perhaps first and foremost an annual reunion that attracts one of the wealthiest, most powerful football crowds in the country. For 49 of 127 matches, a graduate of Harvard or Yale has occupied the Oval office.

“It’s not networking that goes on there, since most people who are going are already pretty well networked,” Mr. Pataki said. “It’s more just having fun and gloating on Monday when you go back to work.”

Yale University, which is leading the series against Harvard by 65-50-8 (Though one of the eight ties, in 1968, is disputed, with a famous headline in Harvard’s student newspaper that declared the 29-29 score a Harvard win) is the favorite to win this year. “Honestly, we’re a good team, but Yale’s probably a great team,” the director of athletic communications at Harvard, Kurt Svoboda, said.

The last time both teams played each other undefeated, the actor Tommy Lee Jones — a former roommate of Vice President Gore — played as an offensive lineman for Harvard. This year’s starting fullback for Harvard, Noah Van Niel, is an aspiring opera singer who sang two weeks ago on the CBS morning show.

For many attendees, the main attraction is in the parking lot.

“The tailgating is unbelievable,” the associate director of the Ivy League, Brett Hoover, said. “People come with candelabrum and lobster and go all out.” The tailgating kicks off at 9 a.m.

Yale officials this year are allowing each Yale residential college and Harvard house to bring in only one large vehicle to the undergraduate parking lot.

For New Yorkers who can’t make it to the game, the Harvard and Yale Clubs in Manhattan are both hosting parties and televising the game.

“I’ve been going to the Harvard-Yale game for most of the last 61 years,” the chairman of Buckingham Capital Management who graduated from Yale in 1950, Lawrence Leeds, said. “It’s a homecoming for ancient Yalies of an old vintage.”

Mr. Leeds, a major donor to the university, said that one dark cloud hangs over this weekend’s festivities. “A terrible fate has befallen my family,” Mr. Leeds said. “My grandson just received early admission at Harvard.”