The New York Giants are dealing with the terminal illness of one of their co-owners for the second time in less than a month. Robert Tisch, 79, who purchased 50 percent of the team in 1991, has inoperable brain cancer. On Oct. 25, Wellington Mara, who had co-owned the team since 1930, died of cancer at 89. His son John, the team's executive vice president and chief operating officer, has overseen the team's operations for the last several years. On Saturday, the day before they faced the Minnesota Vikings at Giants Stadium, general manager Ernie Accorsi, head coach Tom Coughlin and players Tiki Barber and Michael Strahan visited Tisch at his home in Manhattan. Sons Steve, the Giants' executive vice president; and Jonathan, the team's treasurer; addressed the players after practice the same day. "Probably with all his assets, with all his recognition, with all his titles, the one job in his life that he most loved was co-owner of the Giants," Jonathan told the team. "My father loved the players. He loved the organization.