On May 31, 1964 — At Shea Stadium, the New York Mets and the San Francisco Giants play the longest doubleheader in major league history – 9 hours, 52 minutes – with the help of a 23-inning game in the nightcap that is won by the visiting Giants, 8 – 6, on run-scoring hits by Del Crandall and Felipe Alou against Galen Cisco. Gaylord Perry will get the win pitching 10 innings in relief.

 

The game takes 7:23 to play. In the opener, Juan Marichal pitches a complete game and Orlando Cepeda goes 3 for 4 with two runs and one RBI for a Giants 5 – 3 victory.

 

Source:
Baseball Reference May 31