Eli Manning has only played for the New York Giants.
These two teams have not played in the Championship game since 1958.
The Colts and Giants never met in a Super Bowl. They did meet in "The Greatest Game Ever Played," the NFL Championship game of 1958, almost ten years before the first Super Bowl. The last Super Bowl the Giants played in was Super Bowl 42 in 2008. Eli Manning led the Giants to victory over the New England Patriots. The last Super Bowl the Colts played was the year before, when Peyton Manning (Eli's big brother) led the Colts to victory over the Chicago Bears.
In the Giants first regular season home game, played October 18, 1925 the Giants lost to the Frankford Yellow Jackets, 14-0.
The Giants first ever game was an exhibition game against All New Britain on October 4, 1925. The Giants won 26-0. The New York Giants first game in the NFL was played October 11, 1925 against the Providence Steam Rollers. The Giants lost 14-0.
The Seahawks defeated the Colts 24-21 in the first preseason game of the 1998 season, on August 8, 1998, the first game ever played by Peyton Manning.
The Giants' first regular-season game in San Francisco was played April 15, 1958 against the Los Angeles Dodgers. The Giants won 8-0.
The New York Yankees and the New York Giants played the first game of the 1923 World Series in the home park of the Giants called the Polo Grounds.
First of all, I think you meant 'their'. Sorry, maybe you knew that, it just bugs me. Anyway, in the first game of the season, the Colts beat the New York Giants in a game between brothers: Eli (NY Giants) and Peyton (Colts) Manning, both starting quaterbacks.
The very first game of the 2006 regular season was between the Indianapolis Colts and the New York Giants. Both Peyton and Eli started. The Colts won. In the rematch played on September 19, 2010, the Colts won again.
Chicago
The first regular season game in San Francisco was played April 15, 1958 against the Los Angeles Dodgers. The Giants won 8-0.